Real-Time Performance of Dynamic Memory Allocation Algorithms

Synology DiskStation DS918+ is a 4-bay NAS designed for small and medium-sized businesses and IT enthusiasts. Powered by a new quad-core processor, DS918+ provides outstanding performance and data encryption acceleration along with real-time transcoding of 4K Ultra HD source contents. Synology DS918+ is backed by Synology’s 3-year limited warranty.DiskStationDS918+Highlights• Powerful and scalable 4-bay NAS for growing businesses• Encrypted sequential throughput at over 225 MB/s reading and 221 MB/s writing 1• Quad-core processor with AES-NI hardware encryption engine• 4GB DDR3L-1866 memory, expandable up to 8GB• Dedicated M.2 NVMe SSD slots for system cache support• Dual 1GbE LAN with failover and Link Aggregation support• Scalable up to 9 drives with Synology DX5172• Advanced Btrfs file system offering 65,000 system-wide snapshots and 1,024 snapshots per shared folder • Dual-channel H.265/H.264 4K video transcoding on the fly 3High-speed Scalable Storage ServerSynology DS918+ is a 4-bay network attached storage solution equipped with an quad-core processor and 4GB DDR3L memory (expandable up to 8GB). With Link Aggregation enabled, DS918+ delivers great sequential throughput performance at over 226 MB/s reading and 222 MB/s writing 1. With AES-NI hardware accelerated encryption, DS918+ delivers encrypted data throughput at over 225 MB/s reading and 221 MB/s writing 1. DS918+ newly supports M.2 NVMe 2280 SSDs , allowing fast system cache creation without occupying internal drive bays.DS918+ can supp ort up to 9 drives when connected to one Synology DX5172 expansion unit. Storage capacity can be expanded according to your business needs with minimal effort.Btrfs: Next Generation Storage EfficiencyDS918+ introduces the Btrfs file system , bringing the most advanced storage technologies to meet the management needs of modern businesses:• Built-in data integrity check detects data and file system corruption with data and meta-data checksums and improves the overall stability.• Flexible Shared Folder/User Quota System provides comprehensive quota control over all user accounts and shared folders.• Advanced snapshot technology with customizable backup schedule allows up to 1,024 copies of shared folder backups in a minimum 5-minute interval without occupying huge storage capacity and system resources.• File or folder level data restoration brings huge conveniences and saves time for users who wish to restore only a specific file or folder.• File self-healing : Btrfs file system can auto-detect corrupted files with mirroredmetadata, and recover broken data using the supported RAID volumes, which include RAID1, 5, 6, and 10.Comprehensive Business ApplicationsPowered by the innovative Synology DiskStation Manager (DSM), DS918+ comes fully-equipped with applications and features designed specifically for small or growing businesses:• Windows® AD and LDAP support allow easy integration with existing business directory services, without needing to recreate user accounts.• Windows ACL support provides fine-grained access control and efficient privilege settings, allowing DS918+ to fit seamlessly into current infrastructure.• Internet file access is simplified by the encrypted FTP server and Synology File Station , a web-based file explorer. HTTPS, firewall, and IP auto-block support ensure file sharing over the Internet is protected with a high level of security.• Application Privileges controls access to applications and packages based on each individual account, user group, or IP address.• MailPlus allows your business to set up a secure, reliable, and private mail server while giving your employees a modern mail client for receiving and sending messages.• The powerful Collaboration Suite integrates Synology Office , Calendar , and Chat , ensuring secure and effective private communications and allowing your organizations to easily manage and control relevant contents.Virtualization SolutionsSynology’s Virtual Machine Manager opens up abundant possibilities, allowing you to set up and run various virtual machines, including Windows , Linux , and Virtual DSM . You can also test new software versions in a sandbox environment, isolate yourcustomers' machines, and increase the flexibility of your DS918+ with reduced hardware deployment and maintenance costs.Synology iSCSI storage fully supports most of the virtualization solutions, enhancing work efficiency with an intuituve management interface. VMware vSphere™ 6.5 and VAAI integration help offload storage operations and optimize computation efficiency. Windows Offloaded Data Transfer (ODX) speeds up data transfer and migration rate, while OpenStack Cinder support transforms your Synology NAS into a block-based storage component.4K Ultra HD Multimedia LibrarySynology DiskStation DS918+ features real-time transcoding for up to 2 channels of H.264/H.265 4K videos at the same time, bringing more powerful support to thelatest multimedia formats and contents. With Video Station , you can organize personal digital video library with comprehensive media information, and watch 4K Ultra HD movies and films. The intuitive design of Photo Station allows you to effortlessly organize photos into customized categories, smart albums and blog posts, and link them to social networking websites within a few clicks. Audio Station comes with Internet radio and lossless audio formats support, and provides music playback viaDLNA and AirPlay®-compliant devices.Virtual Machine Manager Virtual Machine Manager implements various virtualization solutions, allowing you to manage multiple virtual machines on your DS918+, including Windows , Linux , and Virtual DSM.Synology Collaboration SuiteA powerful and secure private cloud solution for business collaboration and organization, offering intuitive yet effective management options.Hardware OverviewTechnical SpecificationsHardwareCPUIntel Celeron J3455 quad-core 1.5GHz, burst up to 2.3GHz Hardware encryption engine Yes (AES-NI)Hardware transcoding engine • Supported codecs: H.264 (AVC), H.265 (HEVC), MPEG-2, VC-1• Maximum resolution: 4K (4096 x 2160)• Maximum frames per second (FPS): 30Memory4 GB DDR3L SO-DIMM (expandable up to 8 GB)Compatible drive type • 4 x 3.5" or 2.5" SATA SSD/HDD (drives not included)• 2 x M.2 NVMe 2280 SSD (drives not included)External port • 2 x USB 3.0 port • 1 x eSATA port Size (HxWxD)166 x 199 x 223 mm Weight 2.28 kg LAN2 x 1GbE (RJ-45)Wake on LAN/WAN Yes Scheduled power on/off YesSystem fan2 (92 x 92 x 25 mm)AC input power voltage 100V to 240V AC Power frequency 50/60Hz, single phase Operating temperature 5°C to 40°C (40°F to 104°F)Storage temperature -20°C to 60°C (-5°F to 140°F)Relative humidity5% to 95% RH Maximum operating altitude5,000 m (16,400 ft)1Status indicator2Drive status indicator 3Drive tray lock 4USB 3.0 port 5Power button and indicator 6Drive tray 71GbE RJ-45 port 8Reset button9eSATA port 10Power port11Fan12Kensington Security Slot13USB 3.0 port14M.2 NVMe SSD slot (bottom side)6General DSM SpecificationNetworking protocol SMB, AFP, NFS, FTP, WebDAV, CalDAV, iSCSI, Telnet, SSH, SNMP, VPN (PPTP, OpenVPN ™, L2TP)File system • Internal: Btrfs, ext4• External: Btrfs, ext4, ext3, FAT, NTFS, HFS+, exFAT4Supported RAID type Synology Hybrid RAID (SHR), Basic, JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10Storage management • Maximum internal volumes: 512• Maximum iSCSI targets: 32• Maximum iSCSI LUNs: 256• iSCSI LUN clone/snapshot supportSSD cache SSD read-write cache supportFile sharing capability • Maximum local user accounts: 2,048• Maximum local groups: 256• Maximum shared folders: 512• Maximum concurrent SMB/NFS/AFP/FTP connections: 1,000Privilege Windows Access Control List (ACL), application privilegeDirectory service Windows® AD integration: Domain users login via SMB/NFS/AFP/FTP/File Station, LDAP integration Virtualization VMware vSphere® 6.5, Microsoft Hyper-V®, Citrix®, OpenStack®Security Firewall, encrypted shared folder, SMB encryption, FTP over SSL/TLS, SFTP, rsync over SSH, login auto block, Let's Encrypt support, HTTPS (Customizable cipher suite)Supported client Windows 7 and 10, Mac OS X® 10.11 onwardsSupported browser Chrome®, Firefox®, Internet Explorer® 10 onwards, Safari® 10 onwards; Safari (iOS 10 onwards), Chrome (Android™ 6.0 onwards)Interface Language English, Deutsch, Français, Italiano, Español, Dansk, Norsk, Svensk, Nederlands, Русский, Polski, Magyar, Português do Brasil, Português Europeu, Türkçe, Český,Packages and ApplicationsFile Station Virtual drive, remote folder, Windows ACL editor, compressing/extracting archived files, bandwidth control for specific users or groups, creating sharing links, transfer logsFTP Server Bandwidth control for TCP connections, custom FTP passive port range, anonymous FTP, FTP SSL/TLS and SFTP protocol, boot over the network with TFTP and PXE support, transfer logsUniversal Search Offer global search into applications and filesHyper Backup Support local backup, network backup, and backup data to public clouds Active Backup for Server Centralize data backup for Windows and Linux servers without client installationBackup tools DSM configuration backup, macOS Time Machine support, Cloud Station Backup Shared folder sync - maximum tasks: 8Cloud Station Suite Sync data between multiple platforms by installing the client utilities on Windows, Mac, Linux, Android and iOS devices, while retaining up to 32 historical versions of filesMaximum concurrent file transfers: 1,000Cloud Sync One or two-way synchronization with public cloud storage providers including Amazon Drive, Amazon S3-compatible storage, Baidu cloud, Box, Dropbox, Google Cloud Storage, Google Drive, hubiC, MegaDisk, Microsoft OneDrive, OpenStack Swift-compatible storage, WebDAV servers, Yandex DiskSurveillance Station Maximum IP cameras: 40 (total of 1,200 FPS at 720p, H.264) (includes two free camera licenses; additional cameras require the purchasing of additional licenses)Virtual Machine Manager Deploy and run various virtual machines on Synology NAS, including Windows, Linux, or Virtual DSM High Availability Manager Reduce service downtime by setting up two identical NAS into one high-availability clusterSnapshot Replication • Maximum replications: 64• Maximum shared folder snapshots: 1,024• Maximum system snapshots: 65,536Active Directory Server A flexible and cost-effective domain controller solutionVPN Server Maximum connections: 20, supported VPN protocol: PPTP, OpenVPN™, L2TP/IPSecMailPlus Server Secure, reliable, and private mail solution with high-availability, load balancing, security and filtering design (Includes 5 free email account licenses; additional accounts require the purchasing of additional licenses)MailPlus Intuitive webmail interface for MailPlus Server, customizable mail labels, filters, and user interfaceCollaboration tools • Chat maximum users: 1,500• Office maximum users: 200, maximum simultaneous editing users: 80• Calendar: support CalDAV and access via mobile devicesNote Station Rich-text note organization and versioning, encryption, sharing, media embedding and attachmentsStorage Analyzer Volume and quota usage, total size of files, volume usage and trends based on past usage, size of shared folders, largest/most/least frequently modified filesAntivirus Essential Full system scan, scheduled scan, white list customization, virus definition auto updateSYNOLOGY INC.Synology is dedicated to taking full advantage of the latest technologies to bring businesses and home users reliable and affordable ways to centralize data storage, simplify data backup, share and sync files across different platforms, and access data on-the-go. Synology aims to deliver products with forward-thinking features and the best in class customer services.Copyright © 2017, Synology Inc. All rights reserved. Synology, the Synology logo are trademarks or registered trademarks of Synology Inc. Other product and company names mentioned herein may be trademarks of their respective companies. Synology may make changes to specification and product descriptions at anytime, without notice.DS918+-2017-ENU-REV003Headqu artersSynology Inc. 3F-3, No. 106, Chang An W. Rd., Taipei, Taiwan Tel: +886 2 2552 1814 Fax: +886 2 2552 1824ChinaSynology Shanghai 200070, Room 516, No. 638 Hengfeng Rd., Zhabei Dist. Shanghai, ChinaUnited KingdomSynology UK Ltd.Unit C, Denbigh WestBusiness Park, Third AvenueBletchley, Milton KeynesMK1 1DH, UKTel: +44 1908 366380GermanySynology GmbHGrafenberger Allee125 40237 DüsseldorfDeutschlandTel: +49 211 9666 9666North & South AmericaSynology America Corp.3535 Factoria Blvd SE #200Bellevue, WA 98006, USATel: +1 425 818 1587FranceSynology France SARL39 rue Louis Blanc, 92400Courbevoie, FranceTel: +33 147 176288Download Station Supported download protocols: BT, HTTP, FTP, NZB, eMule, Thunder, FlashGet, QQDL Maximum concurrent download tasks: 80Web Station Virtual host (up to 30 websites), PHP/MariaDB®, 3rd-party applications supportOther packages Video Station, Photo Station, Audio Station, DNS Server, RADIUS Server, iTunes® Server, Log Center, additional 3rd-party packages are available in Package CenteriOS/Android™ applications DS audio, DS cam, DS cloud, DS file, DS finder, DS get, DS note, DS photo, DS video, MailPlus Windows Phone® applications DS audio, DS file, DS finder, DS get, DS photo, DS videoEnvironment and PackagingEnvironment safety RoHS compliantPackage content • DS918+ main unit x 1• Quick Installation Guide x 1• Accessory pack x 1• AC power adapter x 1• RJ-45 LAN cable x 2Optional accessories • D3NS1866L-4G• Expansion Unit DX517• VisualStation VS360HD, VS960HD • Surveillance Device License Pack • MailPlus License PackWarranty 3 years*Model specifications are subject to change without notice. Please refer to for the latest information.1. Performance figures may vary depending on environment, usage, and configuration.2. DS918+ supports one Synology DX517, sold separately.3. DS918+ can transcode 4K video to 1080p or lower. The maximum number of concurrent video transcoding channels supported may vary depending on the video codec, resolution,bitrate and FPS.4. exFAT Access is purchased separately in Package Center.。

单片机相关名词英语Ch1 Hardware System of Single Chip Microcomputer PC （Personal Computer）机中央处理单元（CPU，Central Processing Unit）输入输出（I/O，Input/Output）随机存取存储器（RAM，Random Access Memory）专用寄存器（Special Function Register）程序计数器（PC，Program Counter）程序状态字（PSW，Program Status Word）堆栈指针（SP，Stack Pointer）时钟电路（Clock circuit）复位电路（Reset circuit）电压（Voltage）地线（Ground）Ch2 The Exploitation of Single Chip Microcomputer仿真器（emulator）工具软件（facility and software）电源（ power supply）通信电缆（Communication Cable）运行（Execute）、仿真插座（Emulator socket ）单步运行（Step）、在线仿真功能 (On-line emulator function)跟踪运行（Trace）在线仿真器（In Circuit Emulator，简称ICE）断点运行（Breakpoint）Ch3 Instruction System of the MCS-51MCS（Micro Computer System）指令系统（Instruction System）寻址方式（Look for address mode）直接（Directness）立即（Immediately）间接（Indirectly）变址（Change address）相对（Comparatively）数据传送指令（Data Move Instruction）算术运算指令（ Arithmetic Operation Instruction）逻辑运算指令（Logic Operation Instruction）控制转移指令（Control Transfer Instruction）位操作指令（Bit Operation Instruction）BCD码，（Binary Coded Decimal）加法（ADD，Addition）减法（SUB，Subtration）乘法（MUL，Multiplication）除法（DIV，Divition）数据调整（DA，Data Adjust）加大（INC，Increase）减少（DEC，Decrease）Ch4 The Program Design of Assembly Language 机器语言（Machine Language）汇编语言（Assembly Language）高级语言（High-Level Language）简单程序（simple program）分支程序（ branch program）循环程序（circle or loop program）子程序（Subprogram）Ch5 Time and Interrupt中断（Interrupt）计数器（counter）定时器（Timer）定时器工作方式寄存器（TMOD，Timer mode）定时器控制寄存器（TCON，Timer control）启动定时器（TR，Timer Run）定时器满标志位（TF，Time Full）中断允许寄存器（IE，Interrupt Enable）中断优先权寄存器（Interrupt Priority）交通指挥灯 traffic light倒计时 countdown片 RAM on-chip Data RAMCh6 The Expanded System of Single Chip Microcomputer静态RAM（SRAM，Static Random Access Memory ）动态 RAM DRAM，Dynamic Random Access Memory）快擦写型存储器（Flash Memory）只读存储器（ROM，Read-only Memory）随机存取存储器（RAM，Random AccessMemor）Ch7 The Interface Technology of Single Micro Computer发光二极管（LED，Light Emitting Diode）液晶显示器（LCD，Liquid Crystal Display）模数转换器（A/D Converter，Analogy/Digital Converter）数模转换器（D/A Converter，Digital/Analogy Converter）打印机（Printer）Ch8 Serial Port Communicate Technology串行口（Serial Port）并行口（Parallel Port）外部 external通信（Communication）字符帧（Character frame）波特率（Baud Rate）异步通信（Asynchronous Communication）同步通信（Synchronous Communication）通用异步收发器（UART，Universal Asynchronous Receiver Transmitter）通用同步收发器（USRT，Universal Synchronous Receiver/Transmitter）全双工（FD/FDX，Full Duplex）半双工（Semiduplex）单工（SPX，Simplex）1、interrupt [ˌɪntəˌrʌpt] 中断2、timer[ˌtaɪmə(r)] 定时器3、serial port[ˌsiəriəl pɔ:t] 串口4、Interrupt service 中断服务5、Receive [rɪˌsi:v] 接收6、Send [send] 发送7、Success [səkˌses]成功8、Complete [kəmˌpli:t]完成9、Forward [ˌfɔ:wəd] 前进10、Transmit [trænsˌmɪt] 发送信号11、Flag [flæg] 标志12、Universal [ˌju:nɪˌvɜ:sl]13、Asynchronous [eɪˌsɪŋkrənəs]14、Receiver15、Transmitter注：UART(Universal Asynchronous Receiver/ Transmitter ）通用异步接收器/发送器16、Register [ˌredʒɪstə(r)] 寄存器17、Left[left] 左18、Centre [ˌsentə(r)] 中19、Right [raɪt] 右20、Channel [ˌtʃænl] 通道21、Motor [ˌməutə] 马达22、Circuit [ˌsə:kit] 电路，线路，电流 23、Keil编译错误提示中涉及的英文：1、unprintable character[ʌnˌprɪntəbəl ˌkærəktɚ]不可打印字符2、character[ˌkærəktə(r)] 字符3、identifier[aɪˌdentɪfaɪə(r)] 标识符4、undefined identifier未定义的标识符5、duplicate case value 案例重复值6、Duplicate [ˌdju:plɪkeɪt] 重复51单片机英文缩写全称MCS-51指令（1）数据传送类指令（7种助记符）助记符英文注释功能MOV Move 对部数据寄存器RAM和特殊功能寄存器SFR的数据进行传送 MOVC Move Code 读取程序存储器数据表格的数据传送 MOVX Move External RAM 对外部RAM的数据传送 XCH Exchange 字节交换XCHD Exchange low-order Digit 低半字节交换 PUSH Push onto Stack) 入栈 POP Pop from Stack) 出栈（2）算术运算类指令（8种助记符） ADD Addition 加法ADDC Add with Carry 带进位加法 SUBB Subtract with Borrow 带借位减法 DA Decimal Adjust 十进制调整 INC Increment 加1 DEC Decrement 减1MUL Multiplication、Multiply 乘法 DIV Division、Divide 除法 (3)逻辑运算类指令（10种助记符） ANL And Logic 逻辑与 ORL OR Logic 逻辑或XRL Exclusive-OR Logic 逻辑异或 CLR Clear 清零 CPL Complement 取反 RL Rotate left 循环左移RLC Rotate Left throught the Carry flag 带进位循环左移 RR Rotate Right 循环右移RRC Rotate Right throught the Carry flag 带进位循环右移 SWAP Swap 低4位与高4位交换 (4)控制转移类指令（17种助记符）ACALL Absolute subroutine Call 子程序绝对调用 LCALL Long subroutine Call 子程序长调用 RET Return from subroutine 子程序返回 RETI Return from Interruption 中断返回 JMP Jump Indirect SJMP Short Jump 短转移 AJMP Absolute Jump 绝对转移 LJMP Long Jump 长转移CJNE Compare and Jump if Not Equal 比较不相等则转移 DJNZ Decrement and Jump if Not Zero 减１后不为０则转移 JZ Jump if Zero 结果为０则转移var script = document.createElement('script'); script.src ='static.pay.baidu./resource/baichuan/ns.js'; document.body.appendChild(script);JNZ Jump if Not Zero 结果不为０则转移 JC Jump if the Carry flag is set 有进位则转移 JNC Jump if Not Carry 无进位则转移 JB Jump if the Bit is set) B位为１则转移 JNB Jump if the Bit is Not set B位为０则转移JBC Jump if the Bit is set and Clear the bit 位为１则转移，并清除该位 NOP No Operation 空操作（5）位操作指令（1种助记符） SETB Set Bit 置位伪指令助记符英文注释功能 ORG Origin 汇编起始命令 DB Define Byte 定义字节命令 DW Define Word 定义字命令 EQU Equal 赋值命令DATA Data 数据地址赋值命令 XDATA External Data BIT Bit 位地址符号命令 END End 汇编结束命令 DS 定义存储空间命令不同的微机系统有不同的汇编程序，也就定义了不同的汇编命令。

江苏省怀仁中学2024-2025学年高二上学期10月阶段检测英语试题一、阅读理解Application Developer (SQL) — the Schindler GroupGeneral descriptionRemote Monitoring and Customer Solutions is the global competence centre within the Schindler Group for new service offerings and products. Our mission is to create technical solution implementations for the new business models and enhance customer experience by using cutting edge technology. We are developing digital products from idea to industrialization. To further strengthen our international team, we are looking for an experienced Application Developer with a focus on supporting mission critical SQL databases (SQL Server), with an application based on C#NET, SQL Server and Azure.Role and responsibilities● Monitor and support databases including tuning, optimization, and ongoing maintenance.● Develop high quality solutions, bug fixes and new features with the development teams.● Support users by troubleshooting application issues, identifying root causes, and taking measures accordingly.● Testing and debugging of new applications.Job Type: PermanentWe offer:● Dynamic team, flat hierarchies (扁平化的管理制度) and direct communication● Flexible working hours and home office● Above-average retirement allowance and generous holiday entitlement We look forward to receiving your application!1．What do we know about the Schindler Group?A．It is a website.B．It provides digital service.C．It is an advertising company.D．It provides a part-time position.2．What quality must a job applicant have in order to get this job?A．Technological ability.B．Ability to start new businesses.C．Management experience.D．Experiences in international companies. 3．What benefit can you get from this job?A．Free training on SQL.B．Below-average working hours.C．Generous welfare, D, Remaining in the job permanently.The Earth’s population is expected to reach 9.7 billion by 2050. Experts estimate food production will have to increase by 70 percent to keep pace with that growth. Previous methods of agriculture will soon no longer be an option. According to a 2018 study, we have to turn away from meat and dairy products.U.S. customers have proved themselves willing to test the waters. Americans spent $1.4 billion on plant-based meat in 2021, representing a market share of 2.7 percent of all meat sales. The plant-based food companies claim their burgers use less land and water and produce less greenhouse gases. But, consider the possibility that we left our most promising resource behind in the ocean. Will you swap meat for seaweed?“I think seaweed needs branding(品牌),” says Mark Kulsdom, co-founder of the memorably-named Dutch Weed Burger. As Kulsdom explained Dutch Weed Burgers are vegetarian but for meat eaters. A decade after launching their first product, he and his partners now sell about quarter of a million burgers each year.Ultimately, Kulsdom is striving for a culture change. “I believe we need to raise interest sometimes by using a bit of an unorthodox (非正统的) approach to things,” he adds. “When people get what they already know, it’s not that interesting. When their curiosity is awakened, that’s when new things and ideas can enter their minds.”In 2008, researchers discovered 14,000-year-old seaweed fragments (碎片) in southern Chile that had been pressed into cakes and clearly been cooked. As they wrote in Science, all seaweed recovered at the site are excellent sources of iodine, iron, zinc, protein, hormones and a wide range of elements. Though Mark Kulsdom’s Dutch Weed Burger sounds futuristic, one could argue that they’re revisiting one of the oldest stories we know.4．How are plant-based burgers according to the companies?A．They are healthy.B．They are nutritious.C．They are delicious.D．They are environmentally friendly. 5．What does the underlined word “striving” in Paragraph 4 probably mean?A．Leaving.B．Struggling.C．Preparing.D．Waiting.6．What can we learn from the last paragraph?A．Chile is rich in seaweed.B．Seaweed was the major food source in Chile.C．People have long been using seaweed as food.D．Mark Kulsdom’s Dutch Weed Burger is too futuristic.7．Where is the text most likely from?A．A newspaper.B．A science fiction.C．A travel guide.D．A textbook.I’ve bought many things without thinking too much in my life, but the first one that I found uneasy was a pair of Nike VaporMax shoes. It was in July 2018, and I was mindlessly tapping through Instagram updates while waiting for friends. That’s where I saw the advertisement for the shoes.The order took maybe 15 seconds. Almost as soon as I’d paid, I quickly shook off the excitement that had briefly overtaken me, $190 poorer but with one pair of shoes on their way to my apartment. I had completed some version of the online checkout process a million times before, but never could I remember it being quite so thoughtless.That experience wasn’t the result of any just-to-the-market technology. Instead, a handful of small changes to online shopping had grown into something meaningful: Advertisers were collecting stores of personal information with which to target their advertising. Retailers (零售商) were offering free shipping and free returns on everything — buy now, decide later. The widespread use of online payment shortcuts such as Apple Pay was making it unnecessary to create a new account. “Buy now, pay later” services were beginning to appear at more retailers to soften the blow of spending.In the consumer system, friction refers to anything that slows down a potential buyer on the path toward completing a buying journey. About 70 percent of online shopping carts (购物车) are left unfinished without a sale, which suggests that potential buyers can easily derail their plans tobuy. Sometimes, the realization that you’ll need to get up and get your wallet is enough to prevent you from ending up with a new T-shirt.When buying something feels like making a real choice, you have more opportunities to slow down and consider whether it might be the wrong one. Even with the smoothest shopping experience, there’s still the risk of waste, of future inconvenience, of money lost in the fine print. Frictionless shopping might be convenient, in a sense, but it’s a bad system for making good decisions.8．What happened after the author paid for the pair of Nike shoes?A．He felt a bit regretful.B．He decided to live a healthy life.C．He became very picky about shoes.D．He shared his excitement with his friends.9．What aspect of online shopping is mainly stressed in paragraph 3?A．Its variety.B．Its convenience.C．Its personalization.D．Its competitive pricing.10．What does the underlined word “derail” in paragraph 4 mean?A．Make.B．Show.C．Discuss.D．Stop.11．What advice does the author probably give in the last paragraph?A．Shop online to save time.B．Only shop online for future use.C．Save money by shopping online.D．Think twice before shopping online.The conventional language of career success moves in only one direction: up. If you really succeed, you reach the top. But there is another type of career path. Sideways moves without a promotion or a pay rise, can be a benefit to employees and organizations alike.A study carried out by Donald Sull of the Massachusetts Institute of Technology and his co-authors in 2021 found that the availability of lateral (横向的) career opportunities has a marked impact on keeping employees. When they decided whether to stay in the company or not, chances to move sideways were two and a half times more important than pay. Another paper, by Xin Jin of the University of South Florida and Michael Waldman of Cormell University, concluded that lateral moves did not just benefit organizations: employees who experienced them were morelikely to be promoted and to enjoy higher wage growth later in their careers than employees who did not. You can move up by first moving sideways.The crab-like (螃蟹般的) career has other things going for it. One is that it is a good way to learn new things. As hiring processes increasingly emphasize skills, employers are likely to put comparatively less emphasis on CVs and comparatively more weight on what you know. Messrs Jin and Waldman reason that the upper ranks of companies tend to be people whose capabilities are broad, not deep; that may explain why lateral moves are good for promotion prospects. Along with skills come contacts. Transferring between teams usually means building a bigger internal network. Opening the door to more lateral moves is partly a practical matter. Some bigger employers have “internal talent marketplaces” in which employees can find and apply for jobs elsewhere in the company; smaller firms have fewer such opportunities to offer.Embracing sideways movement also requires the right attitude. Lots of managers like to keep talent to themselves, at the expense of workers and firms. And moving sideways still has less cachet (声望) than moving upwards. Most people find it not so easy to accept.12．How does the author develop paragraph 2?A．By telling personal stories.B．By providing research findings.C．By comparing different career paths.D．By making remarks on scientific reports. 13．What does the underlined sentence in paragraph 3 mean?A．Lateral moves involve gaining new skills.B．Lateral moves are mainly for networking purposes.C．Transferring between teams leads to a larger network.D．Contacts are more important than skills in lateral moves.14．What do many managers think of lateral career moves?A．They are a way to keep talent within the company.B．They are seen as a threat to the manager’s own positions.C．They could potentially lead to talent loss within the team.D．They could contribute to the company's growth in the long run.15．Who may embrace lateral moves?A．Bosses who value short-term profits.B．Employees who are eager for more skills.C．Managers who appreciate long-term stability.D．Job hunters who are interested insmaller firms.How to pick the best place for a much-needed refreshment? If you’re like most people, a simple clue is likely to vary your choice. You will look for the busiest restaurant with the most diners because its popularity is bound to reflect on the quality of food and service. 16 Early diners with no meaningful clues as to which restaurant to choose may have picked their evening eatery at random, for example selecting the place with the nicest name or the smiliest waiter. The following passers-by may have misinterpreted their restaurant choice as a well-informed decision and blindly followed their example. 17 Ever-increasing numbers of customers were attracted to the restaurant in question, which could have led to a bad dinner choice in an overcrowded restaurant.V oluntarily copying other people’s thoughts or choices or simply going with the crowd is often referred to as “herd behaviour.”It is a frequent occurrence amongst humans as well as many other animals, a common example being sheep. 18In an earlier article, I discussed the so-called “wisdom of crowds”, which suggests that average judgements of large groups of people often outperform individual choices. Furthermore, following the crowd appears to offer protection and comfort. 19 Finally, following the herd reduces the effort needed to make a personal or unique decision.20 Contrary to the so-called “wisdom of crowds”, herd behaviours typically rely on so-called “information cascades (瀑布)”, where people take on others’ beliefs or copy their choices without critically appraising the underlying reasons. This frequently leads to the imitation of unreasonable or simply stupid behaviours.A．But is this true?B．It is therefore an easy option.C．After all, there’s “safety in numbers”.D．Herding can appear to make a lot of sense.E．This could have resulted in a snow-balling effect.F．Herd behaviours, while easy to explain, hold significant dangers.G．The number of diners is unlikely to indicate the quality of the meal.二、完形填空At 33, I did something brave, or some would say stupid. I 21 Congress (国会). For years, I had existed safely 22 the scenes in politics as an organizer, but in my heart, I always wanted to run. The polls (投票), however, told a very 23 story. I only got 19 percent of the vote. Despite the result, this was the first time in my entire life that I had done something that was truly brave, where I didn’t worry about being 24 .In 2012, I started a company to teach girls to code. We immediately see our girls’ 25 of not being perfect. When the girls are first learning how to code, she’ll say, “I don’t know what 26 to write.” and shows a 27 text editor. But if the teacher presses undo a few times, she’ll see her student wrote code and then 28 it. Instead of showing the 29 that she made, she’d rather show nothing at all.Some people worry about our budget deficit (赤字), but I worry about our 30 deficit. Most girls are raised to 31 risk and failure. This is 32 women are underrepresented in STEM, in Congress, and pretty much everywhere you look. We have to socialize our girls to be comfortable with 33 , and we’ve got to do it now. We have to teach them to be brave in schools and early in their careers, when it has the most potential to 34 their lives, and we have to show them that they will be loved and 35 not for being perfect but for being courageous.21．A．ran for B．lied to C．voted against D．traded with 22．A．on B．off C．inside D．behind 23．A．classic B．simple C．different D．complex 24．A．risky B．perfect C．stupid D．beautiful 25．A．fear B．effort C．trouble D．struggle 26．A．code B．answer C．deficit D．character 27．A．random B．blank C．marked D．broken 28．A．used B．saved C．cracked D．deleted 29．A．mess B．success C．progress D．difference 30．A．honesty B．bravery C．generosity D．determination 31．A．face B．avoid C．admit D．expect32．A．why B．how C．when D．where 33．A．doubt B．danger C．uncertainty D．imperfection 34．A．earn B．risk C．impact D．enjoy 35．A．inspired B．accepted C．tolerated D．protected三、语法填空阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

MYOTRAC INFINITIDual SEMGThe Manufacturer: Thought Technology Ltd.2180 Belgrave AvenueMontreal, Quebec, CanadaH4A 2L8Product Name: MyoTrac Infiniti System Product #: T9800Device Name: MyoTrac Infiniti Encoder Device #: SA9800•Type BF Equipment •Internally powered equipment•Continuous operation•Read Instruction Manual•The pins of the connectors identified with the ESD warning symbol should not be touched unless ESB precautionary procedures are used.CAUTION•US Federal Law restricts this device to sale by, or on order of, a physician or any otherpractitioner licensed by the law of the state in which he or she practices to use or order theuse of this device.WARNING•Do not operate Active Sensors within 10 feet of an operating cellular phone, similar radio transmitting device, other powerful radio interference producing sources such as arcwelders, radio thermal treatment equipment, x-ray machines, or any other equipment thatproduces electrical sparks. Portable and mobile RF communication equipment can affectthis equipment.•With the MyoTrac Infiniti Encoder SA9800 use only with supplied power supply. GlobTek Part Number WR92B2500LF9P-Y-MED (WR95/WR93/WR97) or GS889•The PC used with MyoTrac Infiniti must be placed outside the patient/client environment(more than 3 meters or 10 feet) or the PC must comply with EN60601-1 (system safety).•After use, the Batteries or the Battery pack must be disposed of in accordance with local, state and federal regulations and laws.•After use, the Disposable Electrodes may be a biohazard. Handle, and when applicable, dispose of these materials in accordance with accepted medical practice and any applicablelocal, state and federal laws and regulations.•Reusable electrodes present a potential risk of cross-infection especially when used onabraded skin, unless they are restricted to a single patient or sterilized between patients. Ifsterilizing electrodes, employ only gas sterilization.•Radiated radio frequency electromagnetic fields can cause performance degradation in the MyoScan-Pro EMG sensor. In the worst case, an RF field strength of 22mV/M can causean increase of 1μV in the signal reading from a MyoScan-Pro sensor. Be sure to keep inmind that a very relaxed muscle should provide an EMG reading of approximately 1-3μV.•This device is capable of generating current densities exceeding 2mA r.m.s./cm² this may require special attention of the operator.•Avoid accidental contact between connected but unused applied parts and other conductive parts including those connected to protective earth.•Explosion Hazard; Do not use in the presence of a flammable anesthetic mixture with air, or with Oxygen or Nitrous Oxide.•Not to be immersed in water.•Take care in arranging patient and sensor cables to avoid risk of patient entanglement or strangulation.•The operator is responsible for ensuring the safety of any devices controlled or triggered by Infiniti equipment or software, or by any software or hardware receiving data from Infinitiequipment. Infiniti equipment must not be configured or connected in such a way thatfailure in its data acquisition, processing or control functions can trigger patient feedbackstimulus that poses an unacceptable level of risk.•Use of any equipment in a biofeedback or stimulation context should be immediatelyterminated upon any sign of treatment-related distress or discomfort.•Not to be connected to a patient undergoing MRI, Electro surgery or defibrillation.•Not for use with patients with undiagnosed pain conditions.•Only use the unit for which it was prescribed.•Do not immerse the unit in water or any other liquid substance.•Do not use if you have symptoms of bladder infection.•Do not use with diminished mental capacity or physical competence limiting the use of the device.•Caution should be used for patients with suspected or diagnosed heart problems.•Caution should be used for patients with suspected or diagnosed epilepsy.•Electrode placement and stimulation settings should be based on the guidance of theprescribing practitioner.•If damage is evident of the unit or accessories, discontinue use and contact your supplierfor further information on repair.•The system should not be used adjacent to or stacked with other equipment, if usedadjacent or stacked the unit should be observed to verify normal operation in theconfiguration in which it will be used.•Use of accessories, transducers or cables other than those specified by ThoughtTechnology ltd may result in increased emissions or decreased immunity of the equipmentto electromagnetic energy.ATTENTION•Sensors and equipment damaged by static electricity are not covered under warranty. Toprevent static discharge from damaging the sensor and/or encoders, use anti-static mats orsprays in your working area. A humidifier may also be used to prevent static environmentsby conditioning hot, dry air. It is recommended that all staff involved with the unit receive anexplanation of the ESD symbol and the precautions described above as a minimum.•Do not apply any electrode gel or equivalent directly on the sensor snaps. Always useelectrodes as a medium between the sensor and the client.•Not for diagnostic purposes, not defibrillator proof, not for critical patient monitoring.•To prevent voiding warranty by breaking connector pins, carefully align white guiding dot onsensor plug with slot on sensor input.•Make sure to remove electrodes from sensor snaps immediately after use.•Do not plug third party sensors directly into instrument inputs. Plug only ThoughtTechnology Active Sensor cable connectors into instrument inputs. All electrodes and thirdparty sensors must be connected to active sensors, either directly or through an adapter.•Remove batteries when the device is not being used for an extended period of time. Pleasedispose of battery following local regulations.INTENDED PURPOSE•Biofeedback, Relaxation & Muscle Re-Education purposes•Relaxation of muscle spasms•Prevention or retardation of disuse atrophy•Increasing local blood circulation•Muscle re-education•Maintaining or increasing range of motionNOTE•No preventative inspections required; maintenance must be performed by qualified personnel.Factory re-calibration can be requested.•The supplier will make available, upon request, circuit diagrams, component parts lists anddescription or other information required for the repair of product by qualified personnel.•The operator must be familiar with typical characteristics of signals acquired by thisequipment, and be able to detect anomalies in the acquired signal that could interfere withtreatment effectiveness. Depending on the importance of signal integrity, it may be advisableto continuously monitor the raw signals, in time and/or frequency domain, while the device isbeing used for biofeedback or other purposes. If anomalies are observed on acquired signals,and if you suspect a problem with electromagnetic interference, contact Thought Technologyfor a technical note on identification and remediation.•This product conforms to standards EN60601-1, EN60601-2-10 and EN60601-2-40; someencoder labeling may indicate superceded standards.MAINTENANCE AND CALIBRATION•Wipe encoder with a clean cloth•Factory testing and calibration ensure equipment accuracy and frequency response. Contact Thought Technology for factory re-calibration if necessary.STORAGE•Store in its original case at up to 90% humidity / 30C°TRANSPORTATION•Transport in its original caseManual # SA9814 Rev 4Guidance and manufacturer’s declaration – electromagnetic immunity The MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment, and that precautions regarding that environment are heeded.Immunity test IEC 60601test level Compliance level Electromagnetic environment –guidanceElectrostatic discharge (ESD) IEC 61000-4-2 ±6 kV contact±8 kV air±6 kV contact±8 kV airFloors should be wood, concrete orceramic tile. If floors are covered withsynthetic material, the relative humidityshould be at least 30 %.Electrical fast transient/burst IEC 61000-4-4 ±2 kV for powersupply lines±1 kV for input/outputlines±2 kV for powersupply lines±1 kV for input/outputlinesMains power quality should be that of atypical commercial or hospitalenvironment.SurgeIEC 61000-4-5 ±1 kV differentialmode±2 kV common mode±1 kV differentialmode±2 kV common modeMains power quality should be that of atypical commercial or hospitalenvironment.Voltage dips, short interruptions and voltage variations on power supply input linesIEC 61000-4-11 <5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 sec<5 % U T(>95 % dip in U T)for 0,5 cycle40 % U T(60 % dip in U T)for 5 cycles70 % U T(30 % dip in U T)for 25 cycles<5 % U T(>95 % dip in U T)for 5 secMains power quality should be that of atypical commercial or hospitalenvironment. If the user of theMyoTrac Infiniti requirescontinued operation during powermains interruptions, it is recommendedthat the MyoTrac Infiniti bepowered from an uninterruptible powersupply or a battery.Power frequency (50/60 Hz) magnetic field IEC 61000-4-8 3 A/m 3 A/m Power frequency magnetic fieldsshould be at levels characteristic of atypical location in a typical commercialor hospital environment.NOTE U T is the a.c. mains voltage prior to application of the test level.NOTE 1 At 80 MHz and 800 MHz, the higher frequency range applies.NOTE 2 These guidelines may not apply in all situations. Electromagnetic propagation is affected by absorption Field strengths from fixed transmitters, such as base stations for radio (cellular/cordless) telephones and land mobile radios, amateur radio, AM and FM radio broadcast and TV broadcast cannot be predicted theoretically with accuracy. To assess the electromagnetic environment due to fixed RF transmitters, an electromagnetic site survey should be considered. If the measured field strength in the location in which the MyoTrac Infiniti is used exceeds the applicable RF compliance level above, the MyoTrac Infiniti should be observed to verify normal operation. If abnormal performance is observed, additional measures may be necessary, such as reorienting or relocating the MyoTrac Infiniti.Over the frequency range 150 kHz to 80 MHz, field strengths should be less than [V1] V/m.Guidance and manufacturer’s declaration – electromagnetic emissionsThe MyoTrac Infiniti is intended for use in the electromagnetic environment specified below. The customer or the user of the MyoTrac Infiniti should assure that it is used in such an environment.Emissions test Compliance Electromagnetic environment – guidanceRF emissions CISPR 11 Group 1 The MyoTrac Infiniti uses RF energy only for its internal function.Therefore, its RF emissions are very low and are not likely tocause any interference in nearby electronic equipment.RF emissionsCISPR 11Class BHarmonic emissionsIEC 61000-3-2Not applicableVoltage fluctuations/ flicker emissions IEC 61000-3-3 Not applicableThe MyoTrac Infiniti is suitable for use in all establishments,including domestic establishments and those directly connected tothe public low-voltage power supply network that suppliesbuildings used for domestic purposes.Table of ContentsAbout This Guide (9)Chapter 1 (10)Introduction to your MYOTRAC INFINITI™ Dual SEMG Encoder (10)System Requirements (11)MyoTrac Infiniti Components (12)Connection to the Client (15)Connection to the PC (19)Screen Elements (20)Thought Support (20)Settings Menu (21)Chapter 2 (25)SEMG sessions on your MYOTRAC INFINITI™ Dual SEMG Encoder (25)Open SEMG Sessions (25)Script SEMG Sessions (27)Chapter 3 (28)Data Management on your MYOTRAC INFINITI™ Dual SEMG Encoder (28)MyoTrac Infiniti Review (29)Chapter 4 (30)Display Options on your MYOTRAC INFINITI™ Dual SEMG Encoder (30)Displays (30)Chapter 5 (34)Flow on your MYOTRAC INFINITI™ Dual SEMG Encoder (34)Chapter 6 (35)Reference (35)Technical Support and Order Placing (36)Technical Support (36)Product Numbers & Accessories (37)Placing Orders (38)Specifications (39)MyoTrac Infiniti Hardware Copyright Notice (44)About This Guide Welcome to the MYOTRAC INFINITI™ encoder. This guide is designed to help you get up and running quickly with your new encoder. It will describe the operation of the encoder, and how it interfaces to the host personal computer (PC).It walks you through:•Physical Operation of the encoder.• EMG sessions.• Data management.• Display options.After you have become familiar with the key concepts of your new encoder, you can use the rest of this guide as a reference for less common tasks, and also as a source of information if you have problems operating it.Chapter 1 Introduction to your MYOTRAC INFINITI™ Dual SEMG EncoderThis chapter explains the physical interface with the MyoTrac Infiniti Encoder, how to use it for the first time, and how to transfer data to the host PC.Getting to know your MyoTrac Infiniti Dual SEMG EncoderWhat is a MyoTrac Infiniti Dual SEMG Encoder?The MyoTrac Infiniti is the cutting edge in handheld, dual channel Surface Electromyography(SEMG). With it you will be able to deliver targeted and customized treatment directly to the client’s clinically relevant areas.A simple first approach has been adopted in the design of the MyoTrac Infiniti to make it as easyand fast as possible to get the clinical results desired from this powerful device.Customizing the MyoTrac Infiniti to your clinical needs couldn’t be easier; all users input is directed through a series of intuitive and guided screens using touch screen technology.The partnership of the MyoTrac Infiniti with the BioGraph Infiniti PC software enhances yet further the power and flexibility of the MyoTrac Infiniti. This link enables you to transfer session data to the PC for further viewing, analysis and reporting, in real time or post session.System RequirementsTo install the BioGraph Infiniti software, your computer system must meet or exceed the following requirements.•IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P4 speed 3GHz or higher), Desktop or Laptop withtwo monitor capability•Windows 2000/XP Professional or Home edition.•50 - 60 gigabytes hard disk space for video recording and processing. (Thesoftware needs 2.5 gigabytes to installand run on available hard drive space) •Memory, 512 MB of RAM or more•CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor•32 bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on thedesired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •MS Word 97 or higher (for printingpurposes)•Compact Flash Reader (For use with compact flash card only)•Webcam 30 frames per second (for video purposes only)NOTE: When using certain more complex screens, you must adhere to the Recommended Computer Requirements.••IBM PC compatible(Intel/Pentium/Celeron family or AMDK6/Athlon/Duron family, CPU P3speed 1.8 GHz), Desktop or Laptop •Windows 2000/XP Professional or Home edition.•10 - 20 gigabytes hard disk space •(The software needs 2.5 gigabytes to install and run on available hard drivespace)•Memory, 256 MB of RAM or more •CD ROM or DVD drive•SVGA graphic card (1024 x 768) or higher resolution adapter & monitor •16 Bit Sound Blaster compatible sound card & speakers• 1 to 4 USB ports, depending on the desired number of MyoTrac Infinitiencoders•Mouse or compatible pointing device •Word 97 or higher (for printingpurposes)NOTE: For most recent computer requirements contact Thought Technology Ltd for MAR473Update informationPeriodically updates may become available for the BioGraph Infiniti software and for the MyoTrac Infiniti Hardware. Please contact your local distributor or visit our website for further information on how to obtain updates.MyoTrac Infiniti Components•Compact Flash for increased memory capacity and one method for transfer of data to the PC.•USB for real time transfer of data to the PC.•Touch screen enables graphically guided navigation through the software.•Rugged Ergonomic Case, easy to hold or attach to the subject and will withstand the rigors of daily use.•Battery Charging jack for wall connection enables fast built-in battery charging.•Headphone Jack for stereo sound feedback (or use the built-in speaker).•Push button On/Off switch to prevent accidental switching.• 2 Channels of Surface EMG.PowerThere are three basic methods to power the MyoTrac Infiniti unit: Inserting batteries into the battery compartment of the unit, plugging it into the wall using the supplied AC adapter, or plugging it into a powered up computer using a USB cable.The MyoTrac Infiniti is available with battery charging capabilities. It will work with four standard Alkaline AAA batteries available in all consumer electrical stores. It is also possible to run the unit on removable, externally rechargeable batteries. A rechargeable battery pack is supplied with the MyoTrac Infiniti and can be charged while still inside the unit.Note: When changing batteries it is recommended to plug the unit into external power, either USB or wall transformer so that data is not lost. Failure to supply external power will result in data and script loss.The battery compartment cover slides open by pushing up using the notch provided. Place four AAA batteries in the slots, observing the polarity as illustrated. Please note that a diagram of the correct battery polarity is embossed on the inside surface of the compartment.Alternatively it is possible to use a rechargeable battery pack (Thought Technology Part Number MI1028). This battery pack is plugged into the connector in the battery compartment marked BATT. The pack then fits into the normal battery area. Note: only use battery packs from Thought Technology or authorized representative, as use of other battery packs will damage the device.A wall mounted AC power adapter, supplied with the MyoTrac Infiniti, is used to connect the unit toan electrical outlet. This can be used in conjunction with the batteries or without.The unit can also be powered from the computer via the USB cable. The cable is connected to the unit on one side and on the other side to the USB port of the computer. This can be used inconjunction with the batteries or without.Charging the BatteriesNote: exact power supply subject to change without notice.Internal ChargerIf your MyoTrac Infiniti was supplied with a wall mounted AC adapter it is possible to charge the battery pack while it is inserted in the device.Note: Only use Thought Technology Ltd supplied wall mounted chargers with this device. Failure to do so could result in potential injury. Use only GlobTek Part Number WR9אB2500LCP-Y-MED where א= 2 for North America, א=3 for Europe, א=5 for United Kingdom and א=7 for Australia with the exception of Japan where the part number is GS 889.To start the charging plug in either the wall mounted AC adaptor or the USB cable. A full charging cycle from fully empty to fully charged will take approximately 2hrs for AC adaptor and 5.5hrs for the USB cable. The unit can be used while plugged in to either power source. The charging cycle does not need to be completed in full; it can be stopped at anytime by removing the connector.When the unit is turned off while plugged into an external power source, the screen displays a battery symbol. Charging action is shown with an animation of the battery filling up. When the battery is fully charged, the symbol shows a full battery.If the unit is plugged into an external power source while it is turned off, it will start charging within one minute.The state of the battery charging is available by going to the power menu in the settings menu of the device. It indicates the current mode of power and whether the unit is currently charging the batteries.Note: The rechargeable batteries must be fully charged prior to initial use. In order for the batteries to reach full capacity it may be necessary to charge them several times (~2-8) after initial use.MemoryRecorded data can be saved using three methods - choose the one which most closely matches your usage needs. To select saving method, select the Settings menu from the main menu, and tap on the Save icon.•Internal Memory – Limited size, only the statistical summaries are recorded. Specifically, the statistics for 13 open sessions or 9 training sessions (work/rest) or 6 assessment sessions(work/rest + fast-flick + endurance) can be recorded. Data can be lost if the batteries areremoved from the unit for longer than a few minutes.•Compact Flash Card – Most flexible method of data saving: save all the raw data for review on the encoder or for download to the PC. Available in most electronics stores in a range ofmemory sizes. Since all EMG data is recorded, the amount of data that is saved to thecompact flash card depends on the size of the card:hours64MB 1.75128MB 3.5 hours256MB 7 hours512MB 14 hourshours1GB 27.5hours2GB 55.5The encoder is delivered with a protective insert in the compact flash slot. To remove it, push the button next to the slot once to eject the card. The CF card can then be inserted; you willnotice that the CF card can only be inserted one way into the encoder to protect from incorrect insertion. When inserted properly it will be flush with the encoder rear. Follow the procedure above to remove this card when no longer required, and re-insert the protective insert. CFcards require a CF card reader to transfer data to the PC. The CF cards and reader can bepurchased from most computer stores. Before its first use in the encoder, a CF card requires PC formatting using the file manager, then format the card using the BioGraph Infiniti MainApplication. Formatting and transferring CF data to the PC is covered in depth in theBioGraph Infiniti software manual.•Real Time PC Transfer – Connect to the PC via the USB and save and display the data on the PC in real time. See the following section “Connection to the PC”.Attention: Do not remove the CF card without first stopping recording. If the CF card is removed during recording, you will lose all the data for the current session.TappingLike using a mouse on a computer screen the MyoTrac Infiniti allows you to use your finger or a stylus to tap the buttons directly on the screen. The first time you start your handheld unit, or if the power has been disconnected for a while, you will be guided through a set of welcome screens including calibration, time and date setting. The calibration aligns the internal circuitry of theencoder with its touch sensitive screen so that when you tap a button on the screen, the handheld unit can detect exactly which button is being pressed. It is recommended to use a stylus when calibrating the device as it will provide a more accurate calibration than using a finger.Note:Always use a finger or stylus for tapping the screen. Never use a pen, pencil or othermarking or sharp object on the screen.Damage resulting from misuse of the screen is notcovered by the warranty.The software is designed so that once the screen has been calibrated it is possible to use all the buttons with a finger. In many cases the touch sensitive area is greater than the graphicalconstraints of the button allowing for easier operation using a finger. As necessary wipe screen with a dry cloth to clean. Screen protectors are available from good stationary suppliers and are a good way to extending the life of your screen.Connection to the ClientDepending on the type of session you are going to record there are different ways to connect the two channels to the client. Either plug the extender cable into the device directly and connect to the client with EMG electrodes, or plug them into the pre-amplifier and the pre-amplifier into the MyoTrac Infiniti.Attention: When you insert the extender cable (lead wire) into the electrode connector, MAKE SURE THAT NO BARE METAL OF THE PINS IS EXPOSED.Before applying electrodes, be sure the skin surface is cleaned and dried. Make sure theelectrodes are placed firmly to the skin and make good contact between the skin and electrodes.Please consult the clinical guide for information on electrode selection for different placements. The illustration below shows the division of the body into six areas of treatment.Arms and ShouldersHead and NeckAbdominalsBack and ButtocksLegs and HipsWhen connecting a sensor or extender cables, be sure to properly line up the guiding dot on the top of the plug with the notch in the encoder's input socket. Forcing the plug into the jack in any other position may damage your equipment.Using the MyoTrac Infiniti with AC Power Adapter or Connected to a PCThe MyoTrac Infiniti is designed for safe operation on ungrounded AC power sources. However, if you are using the MyoTrac Infiniti while it is connected to an ungrounded AC power source, for best results you may need to follow some simple guidelines for skin preparation and electrode placement. These measures will help to avoid falsely elevated EMG readings while the muscle is at rest.If you notice elevated resting EMG levels not related to the patient’s condition, and if this occurs only when the unit is connected to AC power (directly via the supplied AC adapter or indirectly via a USB connection to the PC), and if it is necessary to run the MyoTrac Infiniti on ungrounded power(i.e. no 3rd ground pin on the AC wall socket or on the PC power supply), try the followingtechniques to improve the readings.First, if you are using a PC with only 2 prongs on the wall plug and you have a grounded outlet (3 pin wall sockets with a working ground), plug the ac adapter into the MyoTrac-Infiniti and into the grounded outlet to provide a ground for the system.If you have no opportunity to ground either the PC or the AC adapter, use the following electrode placement tips:•If the EMG site is located on an extremity or limb, be sure to place the REF (black colored) electrode more proximally (on or closer to the trunk of the body) than the sense electrodes(yellow and blue), and at least ten centimeters away from either sense electrode.•Prepare the skin under all three electrodes, using a product designed for skin preparation prior to electrode application (mild abrasives such as NuPrep are effective).•If you are using Ag/AgCl (silver/silver chloride) electrodes, put some conductive electrode paste or cream on them before applying them to the skin, or try using gel-type rather than dry Ag/AgCl electrodes.Resting EMG readings will not be affected by connection to AC power, in the following cases:•Running the MyoTrac Infiniti stand-alone, with no AC power adapter and no connection to the PC (only on its rechargeable batteries).。

专业音频术语中英文对照AAAC automatic ampltiude control自动幅度控制AB AB制立体声录音法Abeyancd 暂停，潜态A-B repeat A-B重复ABS absolute 绝对的，完全的，绝对时间ABS american bureau of sta ndard美国标准局ABSS auto blank secrion scannin自动磁带空白部分扫描Abstime绝对运行时间A.DEF audio defeat音频降噪，噪声抑制，伴音静噪ADJ adjective附属的，附件ADJ Adjust调节ADJ acoustic delay line声延迟线Admission允许进入，供给ADP acoustic data processo音响数据处理机ADP（T） adapter延配器，转接器ADRES automatic dynamic range expansion syste动态范围扩展系统ADRM analog to digital remaster 模拟录音、数字处理数码唱盘ADS audio distribution system音频分配系统A.DUB audio dubbing配音，音频复制，后期录音ADV advanee送入，提升，前置量ADV adversum对抗ADV advancer相位超前补偿器Adventure 惊险效果AE audio erasing 音频（声音）擦除AE auxiliary equipment辅助设备Aerial 天线AES audio engineering society美国声频工程协会AF audio fidelity 音频保真度AF audio frequency音频频率AFC active field control 自动频率控制AFC automatic frequency control 声场控制Affricate 塞擦音AFL aside fade listen衰减后（推子后）监听A-fader 音频衰减AFM advanee frequency modulation 高级调频AFS acoustic feedback speake声反馈扬声器AFT automatic fine tuning 自动微调AFTAAS advanced fast time acoustic analysis system 高级快速音响分析系统After 转移部分文件Afterglow 余辉，夕照时分音响效果Against 以……为背景AGC automatic gain control 自动增益控制AHD audio high density 音频高密度唱片系统AI advaneed integrated 预汇流AI amplifier in put 放大器输入AI artificial intelligenee 人工智能AI azimuth indicator 方位指示器A-IN 音频输入A-INSEL audio input selection s频输入选择Alarm 警报器ALC automatic level control自动电平控制ALC automatic load control自动负载控制Alford loop爱福特环形天线Algorithm 演示Aliasing量化噪声，频谱混叠Aliasing distortion折叠失真Align alignment校正，补偿，微调，匹配Al-Si-Fe alloy heac铁硅铝合金磁头Allegretto小快板，稍快地Allegro 快板，迅速地Allocation 配置，定位All rating 全（音）域ALM audio level meter音频电平表ALT alternating震荡，交替的ALT alternator 交流发电机ALT altertue 转路ALT-CH alternate channe转换通道，交替声道Alter 转换，交流电，变换器AM amperemeter 安培计，电流表AM amplitude modulation 调幅（广播）AM auxiliary memory 辅助存储器Ambience 临场感，环绕感ABTD automatic bulk tape degausse磁带自动整体去磁电路Ambient 环境的Ambiophonic system 环绕声系统Ambiophony 现场混响，环境立体声AMLS automatic music locate system自动音乐定位系统AMP ampere 安培AMP amplifier 放大器AMPL amplification 放大AMP amplitude 幅度，距离Amorphous head 非晶态磁头Abort 终止，停止（录制或播放）A-B TEST A比较试听Absorber减震器Absorption声音被物体吸收ABX acoustic bass extensionf 氐音扩展AC accumulator充电电池AC adjustment caliration 调节-校准AC alternating current 交流电，交流AC audio coding数码声，音频编码AC audio center音频中心AC azimuth comprator方位比较器AC-3 杜比数码环绕声系统AC-3 RF杜比数码环绕声数据流（接口）ACC Acceleration 加速Accel渐快，加速Accent重音，声调Accentuator 预加重电路Access存取，进入，增加，通路Accessory附件（接口），配件Acryl丙基酰基Accompaniment 伴奏，合奏，伴随Accord 和谐，调和Accordion 手风琴ACD automatic call distributor 自动呼叫分配器ACE audio control erasing音频控制消磁A-Channel A （左）声道Acoumeter 测听计Acoustical声的，声音的Acoustic coloring 声染色Acoustic image声像Across交叉，并行，跨接Across frequency 交叉频率，分频频率ACST access time?取时间Active主动的，有源的，有效的，运行的Active crossover主动分频，电子分频，有源分频Active loudsperker 有源音箱Armstrong MOD 阿姆斯特朗调制ARP azimuth reference pulse方位基准脉冲Arpeggio琶音Articulation 声音清晰度，发音Artificial仿••…的，人工的，手动（控制）AAD active acoustic devide 有源声学软件ABC auto base and chord自动低音合弦Architectural acoustics 建筑声学Arm motor 唱臂唱机Arpeggio single 琶音和弦，分解和弦ARL aeria天线ASC automatic sensitivity control自动灵敏度控制ASGN Assig r分配，指定，设定ASP audio sig nal process in音频信号处理ASS assembl组件，装配，总成ASSEM assemble匚编，剪辑ASSEM Assembl组件，装配，总成Assign指定，转发，分配Assist辅助（装置）ASSY accesso组件，附件AST active servo techonology有源伺服技术A Tempo 回到原速Astigmatism methord 象散法专业音频术语中英文对照 BB band频带B Bit比特，存储单元B Button按钮Babble多路感应的复杂失真BZ buzzer蜂音器Back clamping反向钳位Back drop交流哼声，干扰声Background noise背景噪声，本底噪声Backing copy 副版Backoff倒扣，补偿Back tracking补录Back up磁带备份，支持，预备Backward 快倒搜索Baffle box音箱BAL balanee平衡，立体声左右声道音量比例，平衡连接Bala need已平衡的Balancing调零装置，补偿，中和Balun平衡二不平衡转换器Banana jack香蕉插头Banana bin香蕉插座Banana pin香蕉插头Banana plug香蕉插头Band频段，Band pass带通滤波器Bandwidth频带宽，误差，范围Band存储单元Bar小节，拉杆BAR barye 微巴Bargraph线条Barrier绝缘（套）Base低音Bass低音，倍司（低音提琴）Bass tube 低音号，大号Bassy低音加重BATT battery电池Baud波特（信息传输速率的单位）Bazooka导线平衡转接器BB base band基带BBD Bucket brigade device戽链器件（效果器）B BAT Battery电池BBE特指BBE 公司设计的改善较高次谐波校正程度的系统BC balaneed current平衡电流BC Broadcast con trol 广播控制BCH ba nd chorus分频段合唱BCST broadcas t 无线电）广播BD board仪表板Beat拍，脉动信号Beat cancel switch差拍干扰消除开关Bel贝尔Below下列，向下Be nch工作台Be nd弯曲，滑音Ben der滑音器BER bit error rate 信息差错率BF back feed反馈BF Backfeed flange反馈镶边BF Band filter 带通滤波器BGM background music背景音乐Bias偏置，偏磁，偏压，既定程序Bidirectio nal 双向性的，8 字型指向的Bifess Bi-feedback sou nd system双反馈系统Big bottom低音扩展，加重低音Bin接收器，仓室BNG BNC连接器（插头、插座），卡口同轴电缆连接器Bi naural effect双耳效应，立体声Bin aural syn thesis双耳合成法Bin go意外现象Bit bi nary digit字节，二进制数字，位Bitstream数码流，比特流Bit yield存储单元Bi-AMP双（通道）功放系统Bi-wire 双线（传输、分音）Bi-Wring双线BK break停顿，间断BKR breaker断电器Blamp两路电子分音Bianking关闭，消隐，断路Blaster爆裂效果器Blend融合（度）、调和、混合Block分程序，联动，中断Block Repeat分段重复Block up 阻塞Bloop （磁带的）接头噪声，消音贴片BNC bayonet connectoi卡口电缆连接器Body mike小型话筒Bond接头，连接器Bongo双鼓Boom混响，轰鸣声Boomy嗡嗡声（指低音过强）Boost提升（一般指低音），放大，增强Booth控制室，录音棚Bootstrap辅助程序，自举电路Bond接头，连接器Bongo双鼓Boom混响，轰鸣声Boomy 嗡嗡声（指低音过强）Boost提升（一般指低音），放大，增强Booth 控制室，录音棚Bootstrap 辅助程序，自举电路Bottoming 底部切除，末端切除Bounee合并Bourclon 单调低音Bowl碗状体育场效果BP bridge bypass电桥旁路BY bypass旁通BPC basic pulse gen erat o 基准脉冲发生器BPF band pass filter 带通滤波器Both sides play disc stereo system双面演奏式唱片立体声系统Bottoming 底部切除，末端切除Bounee合并Bourclon单调低音Bowl碗状体育场效果BP bridge bypass电桥旁路BY bypass旁通BPC basic pulse generato基准脉冲发生器BPF band pass filte带通滤波器BPS ba nd pitch shift分频段变调节器BNC bayo net conn ector 卡口电缆连接器Body mike 小型话筒BPS ba nd pitch shift 分频段变调节器BR bregister 变址寄存器BR Bridge电桥Break中止（程序），减弱Breathing喘息效应B.Reso base resolve基本解析度Bridge桥接，电桥，桥，（乐曲的）变奏过渡Bright明亮（感）Brightness明亮度，指中高音听音感觉Brillianee 响亮BRKRS breaker断路器Broadcast广播BTB bass tuba（低音大喇叭BTL balaneed transformer-less桥式推挽放大电路BTM bottom 最小，低音BU backup nuit备用器件Bumper减震器Bus母线，总线Busbar母线Buss母线Busy 占线BUT button按钮，旋钮BW band width频带宽度，带度BYP bypass旁路By path 旁路专业音频术语中英文对照CCan监听耳机，带盒CANCL cance删除CANCL Cancellin消除Cancel取消Cannon 卡侬接口Canon规则Cap电容Capacitanee Mic电容话筒Capacity功率，电容量CAR carrier载波，支座，鸡心夹头Card程序单，插件板Cardioid心型的CATV cable television 有线电视Crispness脆声Category种类，类型Cartridge软件卡，拾音头Carrkioid 心型话筒Carrier载波器Cart转运Cartridge盒式存储器，盒式磁带Cascade串联Cassette卡式的，盒式的CAV constant angular velocity恒角速度Caution 报警CBR circuit board rack电路板架CC con tour correction 轮廓校正CCD charge coupled devic 电荷耦合器件CD compact disc激光唱片CDA current dumping amplifier 电流放大器CD-E compact disc erasabl可抹式激光唱片CDG compact-disc plus graphic^有静止图像的CD唱盘CDV compact disc with video密纹声像唱片CE ceramic陶瓷Clock enable 时钟启动Cell电池，元件，单元Cellar club地下俱乐部效果Cello大提琴CENELEC conn ectcl欧洲标准21 脚AV 连接器Cent 音分Ce ntral earth 中心接地CES consumer electronic show（美国）消费电子产品展览会CF center frequency 中心频率Cross fade软切换CH channel声道，通道Chain传输链，信道Chain play 连续演奏Chamber密音音响效果，消声室CHAN channel通道Change交换Chapter 曲目Chaper skip跳节CHAE character字符，符号Characteristic curve特性曲线Charge 充电Charger充电器ChaseCheck校验CHC chargeCH - off通道切断ChokeChoose 选择ChromaticChurch 教堂音响效果CI cut in CIC cross in terleave cod交叉隔行编码CIRC circulateCircuit 电路CL cancelClassi古典的CleanCLR clea归零Click嘀哒声ClipCLK clock时钟信号CloseCLS控制室监听ClusterCLV ceiling limit value上限值CMP compactCMPT compatibility兼容性CMRR common mode rejection ratioCNT count记数，记数器CNTRL centralCoarse粗调CoaxCoaxial 数码同轴接口CodeCoefficient 系数CoincidentCold 冷的，单薄的ColorCOM comb梳状（滤波）COMB combinationCOMBI combination 组合，混合COMBO combinationCombining集合，结合COMM communicationCommand 指令，操作，信号COMMONCommunieation speed 通讯速度选择COMP comparatorCOMP compensate补偿CompactCompander压缩扩展器CompareCompatibility 兼容CompensateComplex全套设备CopmoserCompressor压缩器CON concentric cableCOMP-EX压扩器CompromiseComputer 计算机，CON con sole操纵台CON con trollerCo ncert 音乐厅效果Con de nser MicrophoneCone type 锥形（扬声器）CONFIGConnect连接，联络CORR correc跟踪充电合唱色彩，半音切入循环取消净化削波，限幅，接线柱关闭，停止音箱阵效果压缩共模抑制比中心，中央CO carry out定位输出同轴电缆码，编码多信号同步染色效果组合音色配合，组合换向的，切换装置公共的，公共地端比较器压缩比拟补偿创意者，作曲者同轴电缆（频率）平衡电脑Concen tric同轴的，同心的控制器电容话筒布局，线路接法校正，补偿，抵消Configuration 线路布局Con firmati on 确认Consent 万能插座Con sole 调音台Consonant 辅音Con sta nt 常数CONT continuous连续的（音色特性）CONT control控制，操纵Contact接触器Content 内容Continue 连续，继续Continue button 两录音卡座连续放音键Co ntour外形，轮廓，保持Con tra次八度Co ntrast对比度CONV con vert变换Contribution 分配Controlled 可控的Controller 控制器CONV conventional常规的CONV convertible可转换的Copy 复制Correlation meter 相关表Coupler耦合Cover补偿Coverage有效范围CP clock pulse时钟脉冲CP control program控制程序CPU中央处理器Create建立，创造CR card reade卡片阅读机CRC cyclic redundancy check循环冗余校验Crescendo渐强或渐弱Crispness?青脆感CRM control room 控制室CROM control read only memory控制只读存储器Crossfader 交叉渐变器Cross-MOD交叉调制Crossover分频器，换向，切断Cross talk声道串扰，串音Crunch 摩擦音CU counting unit 计数单元C/S cycle/second周/秒CSS content scrambling system 内容加密系统CST case style tap 盒式磁带CT current 电流CTM close talking microphone近讲话筒Cue提示，选听Cue clock故障计时钟Cueing提示，指出Cursor指示器，光标Curve （特性）曲线Custom 常规CUT 切去，硬切换early warning 预警专业音频术语中英文对照 DE earth真地，接地E error错误，差错（故障显示）EA earth地线，真地EAR early 早期（反射声）Earphone 耳机Earth terminal 接地端EASE electro- acooustic simulators for engineers Eat 收取信号工程师用电声模拟器，计算机电声与声学设计软件EBU european broadcasting union欧洲广播联盟EC error correction误差校正ECD electrochomeric display电致变色显示器Echo回声，回声效果，混响ECL extension zcompact limitter 扩展压缩限制器Edge tone边棱音ECM electret conden ser microph one 驻极体话筒Edit 编辑ECSL equivale nt con ti nu ous sound level 等级连续声级ECT electr onec con trolled tran smissi on 电控传输ED edit editor 编辑，编辑器EDTV enhanced definition television增强青晰度电视（一种可兼容高青晰度电视）E-DRAW erasable direct after write 可存可抹读写存储器EE errors excepted允许误差EFF effect efficiency效果，作用Effector 操纵装置，效果器Effects generator 效果发生器EFM 8/14 位调制法EFX effect效果EG envelope generator 包络发生器EIA electronec industries association （美国）电子工业协会EIAJ electro nic in dustries associatio n Japa 日本电子工业协会EIN ei nstei n量子摩尔（能量单位）EIN equivale nt in put noise等效输入噪声EIO error in operati on 操作码错误Eject 弹起舱门，取出磁带（光盘），出盒EL electro luminescenceELAC electroacoustic 电声（器件）ELEC electretElectret condenser microphone驻极体话筒ELF extremely low frequencyELEC electrone电子的ElectroacousticsEMI electro magnetic interferenee 电磁干扰EmissionEMP emphasispo加重EMP emptyEmphasis 力口重EMS emergency switchEmulator模拟器，仿真设备EN enablingEnable赋能，撤消禁止指令EncodingEnd 末端，结束，终止EndingENG engineering工程EngineENG land工程接地EnhanceENS ensemble合奏ENS envelope sensationEnvelopmen环绕感EQ equalizer EQ equalizati on 均衡EQL equalizatio n 均衡EOP end of program 程序结束EOP end output末端输出EOT end of tape磁带尾端EP exte nd playi ng record 多曲目唱片EP exte nded play长时间放录，密录EPG edit pulse gen erator编辑脉冲发生器EPS emerge ncy power supply应急电源Equal-loud ness con tour 等响曲线Equipped准备好的，已装备Equitonic 全音Equivale nee 等效值ER erect 设置ER error错误，误差ERA earpho ne 耳机Eraser抹去，消除Erasing擦除，清洗Erasure 抹音Erase消除，消场致发光驻极体极低频电声学发射空载紧急开关启动编码终端，端接法，镶边运行，使用增强，提高，提升群感均衡器，均衡Er early 早期的ERCD extended resolution C［扩展解析度CD EREQ erect equalizer均衡器（频点）位置（点频补偿电路的中点频率）调整ERF early reflectio n 早期反射（声）Ernumber 早期反射声量Error 错误，出错，不正确ES earth swith接地开关ES electrical stimulati on 点激励Escqpe退出ETER eternity无限Euroscart欧洲标准21脚AV连接器Eve nt事件EVF envelope follower包络跟随器（音响合成装置功能单元）EX exciter激励器EX excha nge交换EX expa nding扩展EXB expa nded bass低音增强EXC exciter激励器EXCH excha ng转换Exclusive专用的Excursion偏移，偏转，漂移，振幅EXP expe nde扩展器，动态扩展器EXP export 输出Exponential horn tweeter 指数型高音号角扬声器Expression pedal表达踏板（用于控制乐器或效果器的脚踏装置）EXT exte nd 扩展EXT exterior外接的（设备）EXT external外部的，外接的EXT extra 超过EXTN exte nsion扩展，延伸（程控装置功能单元）Extract轨道提出EXTSN exte nsior扩展，延伸（程控装置功能单元）专业音频术语中英文对照K-M K key 按键Karaoke卡拉0K无人伴奏乐队KB key board键盘，按钮Kerr 克耳效应，（可读写光盘）磁光效应Key键，按键，声调Keyboard 键盘，按钮Key control 键控，变调控制Keyed键控Key EQ音调均衡kHz Kiloherts 千赫兹Kikll 清除，消去，抑制，衰减，断开Killer 抑制器，断路器Kit 设定Knee 压限器拐点Knob 按钮，旋钮，调节器KP key pulse键控脉冲KTV karaoke TV拌唱电视（节目）KX key键控Lesion故障，损害Leslie列斯利（一种调相效果处理方式）LEV level 电平LEVCON level co ntro电平控制Level 电平，水平，级LF low freque ncy 低频，低音LFB local feedback本机反馈，局部反馈LFE lowfreque ncy resp onsef氐频响应LFO low freque ncy oscillation 低频振荡信号LGD long delay长延时LH low high低噪声高输出LH low n oise high output低噪声高输出磁带L.hall large hall 大厅效果Lift 提升（一种提升地电位的装置）Lift up 升起Labial唇音L left 左（立体声系统的左声道）L line线路L link 链路L long长（时间）LA laser激光（镭射）Lag延迟，滞后Lamp 灯，照明灯Land光盘螺旋道的肩，接地，真地Lap dissolve 慢转换Lapp ing SW通断开关Large大，大型Large hall 大厅混响Larigot 六倍音Laser激光（镭射）Latency 空转，待机Lau nchi ng激励，发射Layer层叠控制，多音色同步控制LCD liquid crystal display液晶显示LCR left center right 左中右LD laser visio n disc激光视盘，影碟机LD load负载LDP in put影碟输入LDTV low definition television低分辨率数字电视LCD projictor液晶投影机Lead 通道，前置，输入Lead-in 引入线Leak 漏泄Learn 学习LED light emitti ng deivce发光辐射器，发光器件M main 主信道M master 主控M memory 存储器M mix 混频M moderate 适中的M music 音乐Mac manchester auto code 曼切斯特自动码MADI musical audio digital interface 音频数字接口Main 主要的，主线，主通道，电源MAG magnet 磁铁Magnetic tape 磁带Magnetic type recorder 磁带录音机Main 电源，主要的Major chord 大三和弦Make 接通，闭合Makeup 接通，选配Male 插头，插件MAN manual 手动的，手控Manifold technology （音箱）多歧管技术Manipulate 操作，键控MANP 手动穿插Manual 手动的，人工的，手册，说明书March 进行曲Margin （电平）余量Mark 标志，符号，标记Mash 压低，碾碎Masking 掩蔽Master 总音量控制，调音台，主盘，标准的，主的，总路MAR Matrix矩阵，调音台矩阵（M）,编组Match 匹配，适配，配对Matrix quad system 矩阵四声道立体声系统MAX maximum 最大，最大值MB megabytes 兆字节Mb/s megabytes per sec ond 兆字节/ 秒MC manual control 手控，手动控制MCH multiple chorus 多路合唱MCR multiple cjhannel amplification reverberation 多路混响增强MD mi ni disc光磁盘唱机，小型录放唱盘MD moving coil 动圈式MDL modulation delay 调制延时MEAS measure测量，范围，测试Measure 乐曲的，小节Meas edit 小结编辑MECH mecha nism机械装置MED medium 适中，中间（挡位）Medley 混合Mega bass超重低音MEM memory 存储器，存储，记忆Member 部件，成员Menu 菜单，目录，表格MEQ mono equalizer 单声道均衡器Merge 合并，汇总，融合Meridian 顶点的，峰值Measure 小结Megaphone 喇叭筒Mel 美（音调单位）Menu 菜单，节目表Message 通信，联系Metal 金属（效果声）Metal tape 金属磁带Meter 电平表，表头，仪表Metronome 节拍器MF matched filter 匹配滤波器MF maveform 波形MF middle frequency 中频，中音MFL multiple flange多层法兰（镶边）效果MFT multiplprogramming with a fixed number of tasks 任务数量固定的多通道程序设计MIC micro 微米MIC microphone 话筒，麦克风，传声器Michcho level 话筒混响电平Micro monitor amp 微音监听放大器MICROVERB microcomputer reverb微处理机混响MID middle中间的，中部的，中音，中频MIDI music instrument digital interface电子乐器数字接口MIN minimum 最小，最小值MIN minute 分钟MIND master integrated network device一体化网络总装置Minitrim 微调Minitrue 微机调整Minor chord 小三和弦Mismatch 失配Mistermination 终端失配MIX 混合，音量比例调节Mixer 调音台，混音器MM moving magnet 动磁式MNTR monitor 监控器MNOS metallic nitrogen - oxide semiconductor 金属氮氧化物半导体MO magneto optical 可抹可录型光盘MOC magnet oscillator circuit 主振荡电路MOD mode 状态，方式，模式MOD model 型号，样式，模型，典型的MOD modulation 调制Mode 状态，（乐曲的）调式Mode select 方式选择Mush 噪声干扰，分谐波Mush area 不良接收区Music 音乐，乐曲Music center 音乐中心，组合音响Music conductor 音乐控制器MUT mute 静音，哑音，噪声控制Muting 抑制，消除Multiple 复合的，多项的，多重的MV mean value 平均值MV multivibrator 多谐振荡器MW medium wave 中波MXE mono exciter 单声道激励器MXR mixer 混频器专业音频术语中英文对照M-P N normal 正常，普通，标准N negative 阴极，负极ohm 欧姆（电阻的单位）Oboe 双簧管O/C open circuit 开路OCK operation control key 操作控制键OCL output capacitorless无输出电容功率放大器OCL output co ntrol li ne 输出控制线OCT octave咅频程，八度音OD operations directive 操作指示OD optical density 光密度OD over drive 过激励OFC office 职能OFC oxyge n-free cupreous无氧铜导线Off 关闭，断开Offering 填入，提供Offset （移相）补偿，修饰，偏置OFHC oxygen free high conductivity copper 高导电率无氧铜导线Ohm 欧姆OK确认OL on line 在线，连机OL over load 过载Omnidirectional 无方向性的On 开，接通Once 一次，单次On e-way relay play单向替换放音Online 联机，联线On ly仅仅，只On-mike 正在送话，靠近话筒One touch 单触连接OP output 信号输出OP over pressure过压Open 打开，开启Opera 歌剧Operate 操作，运转Operation 操作，运转Operator 操纵器，合成器算子Optical 数码光缆接口Optical master 激光器Option 选型，选择Optimum 最佳状态OPTOISO optoisolator光隔离器Or 或，或者ORC optimum record ing curre nt 磁头最佳记录电流Orchestra 管弦乐器Organ 风琴，元件Original 原（程序），初始（化）OSC oscillator振荡器，试机信号（一千赫兹）OSC oscillograph示波器OSS optimal stereo sig na最佳立体声信号OTL无输出变压器功率放大器OTR on e-touch time recording 单触式定时录像OTR operati on temperature range 工作温度范围OTR overload time relay过载限时继电器OUT output 输出Outage 中断Out-burst 脉冲，闪光，闪亮Outcome 结果，输出，开始Out let 输出端子，引出线Outline 轮廓线Out phase 反向OVDB重叠录音Overall 轮廓，总体上Overcut 过调制Over drive 过激励Overdubs 叠录Overflow 信号过强Overha ng （激励器）低音延伸调节Overhearing 串音OVLD over lode过载，超负荷Over sampli ng 过取样Overtone 泛音OVWR overwrite 覆盖式录音Proximity effect 近距离效果Prwsnt 突出感PS position位置，状态PSC program switchi ng cen te节目切换中心PSL phase seque nee logi 相位顺序逻辑PSM peak selector memory峰值选择存储器PSM phase shifter module 移相模件PSM pitch shift modulation 交频调制PST posterrior 后面PST preset预置PSU power supply供电Psychological acoustics 心理声学PT power transformer 电源变压器PT portable 便携式PT pulse timer脉冲计时器PTD pan turnout piece delay 声像分支延时PTE private 专用的PTN pattern模式，样式PTN procedure turn 程序变化PU pickup 拾音PU power unit 电源设备Pull 拉，趋向Pull-in 接通，引入Pumping 抽气效应PWR power电源，功率P-P peak-Peal峰-峰值PPD pin gpo ng delay乒乓延时PPG programme pulse gen erator脉冲程序发生器PPI peak program indicator 峰值显示器PPI programmable peripheral interface 程序外部接口PPL peak program leve峰值音量电平PPM peak program meter峰值节目表，峰值音量表PPM pulse phase modulation 脉冲相位调制Pr power rate 功率比PR program register 程序寄存器PRC precision精确，精细，精密度Pre 前置，预备，之前Pre-delay 预延迟PREAMP preamplifier前置放大器Preselection 预选Prese nee临场效果，现场感Preserve保存，维持Preset预置，预调Press按，压Previous向前，前位的PRM parameter 参量PRO professio na 专业的Process处理，加工PROCR processo r 理器PROG program程序，基本音色Prosody 韵律POSTF后置（万分）Power 电源，功率Power amplifier 功率放大器Power dump 切断电源Power out 功率输出Piower supply 电源供给PP peak power峰值功率P plug 插头P positive 正极P pulse脉冲P power 功率PA preamplifier 前置放大器PA public address扩声Pace步速，级数Packed cell积层电池Pack ing图像压缩P-I-P picture in picture 画中画PAD定值衰减，衰减器，（打击乐大按键的）鼓垫Padding统调，使…•平直Paddle 开关，门电路Page —面，（存储器）页面地址，寻找Pair （立体声）配对，比较PAL phase alternation line逐行倒相彩色电视制式PAM pulse amplitude modulation 脉幅调制PAM pole amplitude modulation 极点调幅Pan pano rama声像调节，定位，全景Panel 面板，操纵板，配电盘Panotrope 电唱机Paper cone 纸盆Parallel 并联，平衡PAR（PARAM） paramete 参数，参量，系数Parametric 参量的Part声部数，部分Partial tone 分音，泛音PAS public address systen扩声系统PASC precision adaptive subband coding精密自适应分段编码Pass通过Passive被动，被动分频，功率分频Paste粘贴PAT pattern模仿，型号，图谱特性曲线Patch临时，插接线，用连接电缆插入Patch bay 配电盘Patch board 插线板Path 信号通路Pattern 样式，方式，样板Pause暂停，间歇，停顿PB playback播放，重放PB push button 按钮开关PBASS proper bass active supply system最佳低音重放系统PBC play back con tro重放控制，回放控制PC perceptual cod ing 感觉编码PC program control 程序控制PCB prin ted circuit board 印刷线路板PCC phase correlation cardioid microphone相位相关心形话筒PCM precisi on capacitor microph one 精密电容话筒PD power divider 功率分配器PD power doubler 功率倍增器PD program directive 程序指令PDS programmable data system程序可控系统PE program executi on 程序执行Peak峰值，削波（灯）Peak and dip峰式频率欧洲标准21脚AV接口Pedal踏板PEM pulse edge molulatio n 脉冲边缘调制Pentatonic 五声调式PEQ parameter equalizer参量均衡器PERC percussioi打击乐器PERCUS丁击乐器Performance 施行，表演，表现，演出Permutator 转换开关，变换器Perspective 立体感Perform 执行，完成，施行PFL per fader louder speaker衰减前监听，预监听PG pulse gen erator 脉冲发生器PGM program 节目，程序PH phase 相位PHA phase相位Phantom 幻像电源，幻象供电Phase相位，状态Phase RE\倒相（电路）Phaser移相器Phasi ng相位校正，移相效果Phon 方（响度单位）Phone 耳机，耳机插口Pho neme 音素Pho no （ph ono graph）唱机PHS phase移相器Physiological acoustics生理声学PI phase inv ersio n 倒相PIA peripheral in terface adapter 外围接口适配器Pianotron 电子钢琴Piano 钢琴Piano whine 钢琴鸣声Pilot 指示器，调节器Pilot jack 监听插孔Pin 针型插口，不平衡音频插口Pink n oise粉红噪声Pipe 管，笛Pitch 音高，音调Pitch shifter 变调器，移频器PK peak削波（灯），峰值PL phase lock相位锁定，锁相PL pilot lamp 指示灯PL pre listen预监听，衰减前监听Placeme nt连接方式Plate 金属板效果，板混响器Play 播放，重放，弹奏Playback 播放Player唱机，放音器Plug插头Plunge切入Pop filter 噗声滤除器Pops流行音乐，流行音乐音响效果。

RHEL交换内存（Swap）使⽤率为100%环境Red Hat Enterprise Linux问题Swap memory usage is at 100%Swap memory usage is above the error thresholdSwap memory usage is higher than averageWhy Swap is being used while there is available physical memory?决议Introduction - what is Swap?The primary function of Swap space is to substitute disk space for RAM memory when real RAM fills up and more space is needed.The kernel uses a memory management program that detects blocks, aka pages, of memory in which the contents have not been used recently. The memory management program swaps enough of these relatively infrequently used pages of memory out to a special partition on the hard drive specifically designated for “paging,” or swapping. This frees up RAM and makes room for more data to be entered into your spreadsheet. Those pages of memory swapped out to the hard drive are tracked by the kernel’s memory management code and can be paged back into RAM if they are needed.OverviewRegarding full Swap, multiple points should be taken into consideration:1. On RHEL6, a bug which did lead to increased Swap usage was resolved in kernel-2.6.32-504.el6 () and later. Details can be found in .2. Increasing the system's physical memory will make it less likely that Swap has to be used3. A further approach tries to find the process using most Swap (using below script) and kill that process. This is not desirable in most situations.4. The available Swap space can be increased by creating a swapfile, and this can be done without service downtime. Please refer to for details.5. If it is not desired that current processes have pages which are also in Swap, then swapoff -a, followed by a swapon -a can be performed.Resolution 1: Increase the system's physical memoryIn some cases, full Swap memory issue causes thrashing (continuously heavy Swap in/out activity). When sar files exist in the system (the files are located in /var/log/sa, sysstat package must be installed and sysstat service should run) and a sar file contains continuous pswpin and pswpout record, it indicates that the system does not have enough physical memory in current workload. The system requires additional system memory whose size is at least the current total Swap size. Thrashing usually causes system performance degradation because it leads to heavy disk I/O. Recent systems with SSD might not show such system performance degradation.Example of sar output:12:00:00 AM pswpin/s pswpout/s<snip>05:20:00 AM 0.210.0005:30:00 AM 0.080.8505:40:00 AM 0.470.0005:50:00 AM 3.58 1.7106:00:00 AM 2.480.0006:10:00 AM 39.917.17 <<<<----- example of thrashing06:20:00 AM 0.21 2.7206:30:00 AM 13.30 1.04Resolution 2: Find process's memory regions that are using the most SwapTo find out what 10 process's memory regions are using the most Swap space, copy and paste these commands onto a bash script and then execute it via the terminal:#!/bin/bashps ax -o pid,args | grep -v '^ PID'|sed -e 's,^ *,,' > /tmp/ps_ax.outputecho -n >/tmp/results# SwapPss can provide more accurate output# Only RHEL8 onward availableSWAP_KEYWORD=$(grep -l SwapPss /proc/self/smaps)if [ "$SWAP_KEYWORD" == "" ]; thenSWAP_KEYWORD="Swap"elseSWAP_KEYWORD="SwapPss"fifor swappid in $(grep -l ${SWAP_KEYWORD} /proc/[1-9]*/smaps ); doswapusage=0for x in $( grep ${SWAP_KEYWORD} $swappid 2>/dev/null |grep -v '\W0 kB'|awk'{print $2}' ); dolet swapusage+=$xdonepid=$(echo $swappid| cut -d'' -f3|cut -d'/' -f3)if ( [ $swapusage -ne 0 ] ); thenecho -ne "$swapusage kb\t\t" >>/tmp/resultsegrep"^$pid " /tmp/ps_ax.output |sed -e 's,^[0-9]* ,,' >>/tmp/resultsfidoneecho"top swap using processes which are still running:"sort -nr /tmp/results | head -n 10This will display the 10 processes' memory regions that were using the most Swap since they were started, sorted in decreasing Swap usage order. This script does not typically display total Swap in use by a process. If you kill some of these processes that own the listed memory segments then you will observe a decrease in Swap usage. The processes killed may either be a direct contributor or a victim of the root cause of high Swap usage.Note 1: If the above script produces no output, then it could be that none of the currently running processes in /proc/*/smaps are using Swap. You can test that by simply running: # grep Swap /proc/[1-9]*/smapsIt is Important to keep in mind that the aforementioned script will only show the active processes that have memory swapped at that point in time, meaning at the time when the script was run. It might be possible that the system has already swapped a chunk of memory and that is visible on free output but the script shows no output. Point being, this script shows the current swapping activity and cannot be used for historical data gathering. For that purpose, sar can be used.Note 2: To change the number of processes displayed to something other than 10, modify 'tail -10' to the desired number.Note 3: There is no way to know how much Swap space is used by a process in kernel versions prior to version 2.6.18-128.el5 (RHEL 5 update 3). So in any prior RHELversions (all of RHEL 3, RHEL 4, and RHEL 5 up to and including RHEL 5 update 2) the necessary kernel code for determining how much Swap space is used by individualprocesses is not present.Note 4: This can also be accomplished by running the top command and adding the SWAP column to the output.To add the Swap usage to "top":1. Run top, press "f" to enter the field editor2. Navigate to the SWAP field and select it3. Toggle the display of the column by pressing "d" or "space"4. Press "q" to exit the the field editor and return to the top output5. To permanently add the SWAP column, press "W" while running top. You can confirm this by reviewing ~/.config/procps/toprcYou may expect this field to show how much a program is swapped out.However, this is not always the case, as top natively shows this information by using the below formula:VIRT = SWAP + RES or equalSWAP = VIRT - RESYou can also save the output to a file: quit top and run "top -b -n1 > top_b_n1.txt"Note 5 System V IPC maintains a list of swapped out shared memory (shmem) pages on the shmem_swaplist list. In releases prior to RHEL 5 update 8 (2.6.18-293.el5) theswapped out System V IPC shared memory segments are not exposed to user space. Under newer kernels this information is exported through the /proc/sysvipc/shm file.Example of a partial output:# cat /proc/sysvipc/shmkey shmid perms size cpid lpid nattch uid gid rss swap8337655361600393216967319030210658110658139321600586547316005242889673936421065811065811146884096 <<<-----045875616005242889655106862106581106581512000033000014915251600502169609673190302106581106581104488968716288 <<<-----Resolution 3: Increase Swap spaceTo increase Swap space on your system, follow the instructions in these knowledge base articles:Use this guide to determine how much Swap size the system should have - .In case you are experiencing Swap threshold alerts by a monitoring process/program, consider adding another 4GB of Swap via the terminal command line to your system toreduce the alerts.The example for that command would be:# dd if=/dev/zero of=/swapfile bs=1k count=4MAfterwards, follow the rest of kbase to create and activate the Swap.Note 6 The swapon command accepts a priority option which states which Swap device should be used at first compared to the other Swap devices. The details are written inman 2 swapon.Quote from man 2 swaponEach swap area has a priority, either high or low. The default priority is low. Within the low-priority areas, newer areas are even lower priority than older areas.All priorities set with swapflags are high-priority, higher than default. They may have any nonnegative value chosen by the caller. Higher numbers mean higher priority.Swap pages are allocated from areas in priority order, highest priority first. For areas with different priorities, a higher-priority area is exhausted before using a lower-priority area. If two or more areas have the same priority, and it is the highes priority available, pages are allocated on a round-robin basis between them.Resolution 4: Flushing the SwapAnother option is to flush the Swap by utilizing the following commands:# swapoff -a# swapon -aWarning: Flushing Swap in this way will force the entire contents of swap back into main memory. If your system is already low on memory this may cause it to go into an Out OfMemory condition (OOM). Care and consideration should be taken before using this option. If the system is somewhat low on memory (and not very low) pages may have to bereclaimed while bringing the contents of Swap into memory - and this may degrade performance for a short time.Resolution 5: Clear POSIX shared memory (/dev/shm/)In case you have followed some of the steps above, or all of them, and still have high Swap Memory usage, it might be an overload on the /dev/shm POSIX shared memorydirectory./dev/shm is an implementation of the traditional shared memory concept, and an efficient means of passing data between programs. One program will create a memory portion,which other processes (if permitted) can access.shm / shmfs (also known as tmpfs), is a common name for a temporary file storage facility on many Unix-like operating systems. It is intended to appear as a mounted filesystem, but one which uses virtual memory instead of a persistent storage device.In the example SOS Report analysis below, it can be seen that due to an already high percentage of physical memory usage (~77%= ~390 GB), the overload on the /dev/shm/directory (~252 GB) was Swapped as a whole segment instead of utilizing the available RAM (~114 GB) first.# cat sos_commands/memory/free_-mtotal used free shared buffers cachedMem: 51654439941911712454274123272-/+ buffers/cache: 376105140438Swap: 26316726314423Measuring the approximate RAM used by processes running in the system does explain the high Swap usage# awk'{ SUM += $6 } END { print SUM/1024/1024}'ps359.867If we convert the amount of used memory in /dev/shm to megabytes, we will receive an amount that is close to the memory being used by Swap:264470476/1024 = 258272 MB# egrep"^Filesystem|^tmpfs"dfFilesystem 1K-blocks Used Available Use% Mounted ontmpfs 26447054026447047664100% /dev/shmIn this case the user needs to clean irrelevant files and folders from the POSIX shared memory directory (/dev/shm/), and perhaps even investigate which application wrote into the /dev/shm/ and see if there is an abuse.根源If a system has 64GB of physical memory and 2GB of Swap memory, then it is relatively easy for Swap to become 100% full. This will cause alerts to be triggered on the system where alerts are generated by a kind of system monitoring tool. It is recommended to increase the amount of Swap space to prevent it from becoming 100% full. This will prevent alerts from being generated.Also, it is important to note that in a Linux system, swapping itself is not bad. Any data that is filesystem backed, is never swapped. Only the anonymous pages go into Swap memory. The Linux kernel's page frame reclaim algorithm (PFRA) essentially comes into play in three occasions:1. Out of memory reclaiming - kernel detects a 'low memory' condition.2. Hibernation reclaiming - kernel must free memory because it is entering suspend-to-disk state.3. Periodic reclaiming - kernel employs a thread to reclaim memory periodically.Speaking from a wide perspective, the problem description of this article gleans towards the issue of periodic reclaiming. Here, the 'kswapd' kernel thread is periodically awoken to check whether the number of free memory pages are below the pages_high watermark in a particular memory zone. When it detects such a case, it transfers the anonymous pages to Swap, based on the scanning priority and access time of the page. Over time, those swapped out pages might gather a substantial size, which is then indicated by the monitoring system. However, this mechanism of swapping is in fact, one of the many wonders that memory management subsystem does to improve performance.When Swap memory usage is at 100% in Linux operating systems, it does not necessarily mean it's an issue. If the processes that are using the Swap do not need that memory, and the operating system does not have anything else to put into Swap, then it will be left at 100% without further issues. If this is generating alerts then it is possible to increase the Swap space to stop these alerts, but the system can't be force to not use the Swap memory unless you flush the Swap or start killing processes.诊断步骤Review the output of free commandExample:# free -mtotal used free shared buffers cachedMem: 516544 399419 117124 5427 41 23272-/+ buffers/cache: 376105 140438Swap: 263167 263144 23 <<<<------Review the SAR file output for continuously heavy Swap in/out activity. This is represented by high values of "pswpin" / "pswpout"Example of sar output :12:00:00 AM pswpin/s pswpout/s<snip>05:20:00 AM 0.210.0005:30:00 AM 0.080.8505:40:00 AM 0.470.0005:50:00 AM 3.58 1.7106:00:00 AM 2.480.0006:10:00 AM 39.917.17 <<<<-----06:20:00 AM 0.21 2.7206:30:00 AM 13.30 1.04摘抄： https:///solutions/33375。

常用模块组‎（Commo‎nly Used Block‎s）Integ‎rator‎：积分器模块‎，输出对输入‎时间积分。

Deriv‎ative‎：微分器模块‎，输出对输入‎时间微分。

State‎-Space‎：状态空间表‎达式模块，实现线性状‎态空间系统‎。

Trans‎fer Fcn：传递函数模‎块，实现线性传‎递函数。

Zero-Pole：零极点函数‎模块，实现用零极‎点方式指定‎传递函数。

Trans‎port Delay‎：传输延迟模‎块，以固定的时‎间延迟输入‎。

Varia‎ble Trans‎port Delay‎：可变传输延‎迟模块，以变化的时‎间量延迟输‎入。

Varia‎ble Time Delay‎：可变时间延‎迟模块。

非线性模块‎组（Disco‎ntinu‎ities‎）非线性模块‎组（Disco‎ntinu‎ities‎）Backl‎ash：磁滞回环模‎块。

Satur‎ation‎：饱和非线性‎模块。

Satur‎ation‎Dynam‎ic：动态饱和非‎线性模块。

Dead Zone：死区非线性‎模块。

Dead Zone Dynam‎ic：动态死区非‎线性模块。

Relay‎：继电模块。

Quant‎izer：量化模块。

Coulo‎mb & Visco‎us Frict‎ion：库伦与黏性‎摩擦非线性‎模块。

Rate Limit‎er：静态限制信‎号的变化速‎率。

Rate Limit‎er Dynam‎ic：动态限制信‎号的变化速‎率。

Hit Cross‎ing：过零检测非‎线性模块。

Wrap to Zero：环零非线性‎模块。

离散系统模‎块组（Discr‎ete）离散系统模‎块组（Discr‎ete）Unit Delay‎：单位时间延‎迟，延迟信号一‎个采样周期‎。

Discr‎ete Trans‎fer Fcn：离散系统的‎传递函数，实现离散传‎递函数。

Discr‎ete Zero-Pole：离散系统的‎零极点函数‎Discr‎ete State‎-Space‎：离散系统的‎状态方程，实现离散状‎态空间系统‎。

Impact of JIT JVM Optimizations on Java Application Performance¢K. Shiv , R. Iyer , C. Newburn , J. Dahlstedt , M. Lagergren and O. Lindholm Intel Corporation BEA Systems¢ ¢ ¢ ¡ ¡ ¡ ¡AbstractWith the promise of machine independence and efficient portability, JAVA has gained widespread popularity in the industry. Along with this promise comes the need for designing an efficient runtime environment that can provide high-end performance for Java-based applications. In other words, the performance of Java applications depends heavily on the design and optimization of the Java Virtual Machine (JVM). In this paper, we start by evaluating the performance of a Java server application (SPECjbb2000 ) on an Intel platform running a rudimentary JVM. We present a measurement-based methodology for identifying areas of potential improvement and subsequently evaluating the effect of JVM optimizations and other platform optimizations. The compiler optimizations presented and discussed in this paper include peephole optimizations and Java specific optimizations. In addition, we also study the effect of optimizing the garbage collection mechanism and the effect of improved locking strategies. The identification and analysis of these optimizations are guided by the detailed knowledge of the micro-architecture and the use of performance measurement and profiling tools (EMON and VTune) on Intel platforms.1 IntroductionThe performance of Java client/server applications has been the topic of significant interest in the recent years. The attraction that Java offers is the promise of portability across all hardware platforms. This is accomplished by using a managed runtime engine called the Java Virtual Machine (JVM) that runs a machine-independent representation of Java applications called bytecodes. The most common mode of application execution is based on a Just-InTime (JIT) compiler that compiles the bytecodes into native machine instructions. These native machine instructions are also cached in order to allow for fast re-use of the frequently executed code sequences. Apart from the JIT compilation, the JVM also performs several functions including thread management and garbage collection. This brings us to the reason for our study i.e. Java application performance depends very heavily on the efficient execution of the Java Virtual Machine (JVM). Our goal in this paper is to characterize, optimize and evaluate a JVM while running a representative Java application. Over the last few years, several projects (from academia as well as in the industry) [1,2,4,7,8,9,10,15,16,21] have studied various aspects of Java applications, compilers and interpreters. We found that R. Radhakrishnan et al. [16] cover a brief description of much of the recent work on this subject. In addition, they also provide insights on architectural implications of Java client workloads based on SPECjvm98 [18]. Overall, the published work can be classified into the following general areas of focus: (1) presenting the design of a compiler, JVM or interpreter, (2) optimizing a certain aspect of Java code execution, and (3) discussing the application performance and architectural characterization. In this paper, we take a somewhat different approach touching upon all the three aspects listed above. We present the software architecture of a commercial JVM, identify several optimizations and characterize the performance of a representative Java server benchmark through several phases of code generation optimizations carried out on a JVM. Our contributions in this paper are as follows. We start by characterizing SPECjbb2000 [17] performance on Intel platforms running an early version of BEA’s JRockit JVM [3]. We then identify various possible optimizations (borrowing ideas from literature wherever possible), present the implementation details of these optimizations in the JVM and analyze the effect of each optimization on the execution characteristics and overall performance. Our performance characterization and evaluation methodology is based on hardware measurements on Intel platforms - using performance counters (EMON) and a sophisticated profiler (VTune [11]) that allows us to characterize various regions of software execution. The code generation enhancements that we implement and evaluate include (1) code quality improvements such as peephole optimizations, (2) dynamic code optimizations, (3) parallel garbage collection and (4) fine-grained locks. The outcome of our work is the detailed analysis and breakdown of benefits based on these individual optimizations added to the JVM. The rest of this paper is organized as follows. Section 2 covers a detailed overview of the BEA JRockit JVM, the measurement-based characterization methodology and the SPECjbb2000 benchmark. Section 3 discusses the opti-¤ ¥£2 Background and MethodologyIn this section, we present a detailed overview of JRockit (the commercial JVM used) [3], SPECjbb2000 (the Java server benchmark) [17] and the optimization and performance evaluation methodology and tools.Figure 1. The SPECjbb2000 Benchmark Process2.1 Architecture of the JRockit JVMThe goal of the JRockit project is to build a fast and efficient JVM for server applications. The virtual machine should be made as platform independent as possible without sacrificing platform specific advantages. Some of the considerations included reliability, scalability, nondisruptiveness and of course, high performance. JRockit starts up differently from most ordinary Java JVMs by first JIT-compiling the methods it encounters during startup. When the Java application is running, JRockit has a bottleneck detector active in the background to collect runtime statistics. If a method is executed frequently and found to be a bottleneck, it is sent to the Optimization Manager subsystem for aggressive optimization. The old method is replaced by the optimized one while the program is running. In this way, JRockit is using adaptive optimization to improve code performance. JRockit relies upon a fast JIT-compiler for unoptimized methods, as opposed to interpretative byte-code execution. Other JVMs such as Jalapeno/Jikes [23] have used similar approaches. It is important to optimize the garbage collection mechanism in any JVM in order to avoid disruption and provide maximum performance to the Java application. JRockit provides several alternatives for garbage collection. The ”parallel collector” utilizes all available processors on the host computer when doing a garbage collection. This means that the garbage collector runs on all processors, but not concurrently with the Java program. JRockit also has a concurrent collector which is designed to run without ”stopping the world”, if non-disruptiveness is the most important factor. To complete the server side design, JRockit also contains an advanced thread model, that makes it possible to run several thousands of Java threads as light weight tasks in a very scalable fashion.The database component requirement common to three-tier workloads is emulated using binary trees of objects. The clients are similarly replaced by driver threads. Thus, the whole benchmark runs on a single computer system, and all the three tiers run within the same JVM. The benchmark process is illustrated in Figure 1. The SPECjbb2000 application is somewhat loosely based on the TPC-C [20] specification for its schema, input generation, and operation profile. However, the SPECjbb2000 benchmark only stresses the server-side Java execution of incoming requests and replaces all database tables with Java classes and all data records with Java objects. Unlike TPC-C where the database execution requires disk I/O to retrieve tables, in SPECjbb2000 disk I/O is completely avoided by holding the objects in memory. Since users do not reside on external client systems, there is no network IO in SPECjbb2000 [17]. SPECjbb2000 measures the throughput of the underlying Java platform, which is the rate at which business operations are performed per second. A full benchmark run consists of a sequence of measurement points with an increasing number of warehouses (and thus an increasing number of threads), and each measurement point is work done during a 2-minute run at a given number of warehouses. The number of warehouses is increased from 1 until at least 8. The throughputs for all the points from N warehouses to 2*N inclusive warehouses are averaged, where N is the number of warehouses with best performance. This average is the SPECjbb2000 metric.2.3 Performance Optimization and Evaluation MethodologyThe approach that we have taken is evolutionary. Beginning with an early version of JRockit, performance was analyzed and potential improvements were identified. Appropriate changes were made to the JVM and the new version of the JVM was then tested to verify that the modifications did deliver the expected improvements. The new version of the JVM was then analyzed in its turn for the next stage of performance optimizations. The types of performance optimizations that we investigated were two-fold. Changes were made to the JIT so that the quality of the generated code was superior, and changes were made to other parts of the JVM, particularly to the Garbage Collector, Object Allo-2.2 Overview of the SPECjbb2000 BenchmarkSPECjbb2000 is Java Business Benchmark from SPEC that evaluates the performance of Server Side Java. It emulates a three-tier system, with business logic and object manipulation, the work of the middle layer predominating.$ ' i7 f  8"" h g`e V (d"cb #! '6 § a X  & !! ' § $ '$1 Y "! (#© W"   %$V T S RE BIHG FE D A U(QP 3(#3 BC 3 9@  &! ¦ &6 4 $ $© #! (87 #(¨5$ #! 321 " # 0 $ ' ' ' "#) ( & $ #!  %© $ #"  !   © §   ¨¦mizations - how they were identified, implemented and their performance evaluation. Section 4 summarizes the breakdown of the performance benefits and where they came from. Section 5 concludes this paper with some direction on future work in this area.Figure 2. Processor Scaling on an early JRockit JVM version2.4.2 VTune Performance Monitoring Tool Intel’s VTune performance tools provide a rich set of features to aid in performance analysis and tuning: (1) Timebased and event-based sampling, (2) Attribution of events to code locations, viewed in source and/or assembly, (3) Call graph analysis and (4) Hot spot analysis with the AHA tool, which indicates how the measured ranges of event count values compare with other applications, and which provides some guidance on what other events to collect and how to address common performance issues. One of the key tools provides the means for providing the percentage contribution of a small instruction address range to the overall program performance, and for highlighting differences in performance among versions of applications and different hardware platforms.2.4 Overview of Performance Tools - EMON and VTuneThis section describes the rich set of event monitoring facilities available in many of Intel’s processors, commonly called EMON, and a powerful performance analysis tool based on those facilities, called VTune [11].2.4.1 EMON Hardware and Events Used The event monitoring hardware provides several facilities including simple event counting, time-based sampling, event sampling and branch tracing. A detailed explanation of these techniques is not within the scope of this paper. Some of th key EMON events leveraged in our performance analysis include (1) Instructions – the number of instructions architecturally retired, (2) Unhalted cycles – the number of processor cycles that the application took to execute, not counting when that processor was halted, (3) Branches – the number of branches architecturally retired which are useful for noting reductions in branches due to optimizations, (4) Branch Mispredictions – the number of branches that experienced a performance penalty on the order of 50 clocks, due to a misprediction, (5)Locks – the number of locked cmpxchg instructions, or instructions with a lock prefix and (6) Cache misses – the number of misses and its breakdown at each level of the cache hierarchy. The reader is referred to the Pentium 4 Processor Optimization Guide [24] for more details on these events.3 JVM Optimizations and Performance ImpactIn this section we describe the various JVM improvements that we studied and document their impact on performance. We also show the analysis of JVM behavior and the identification of performance inhibitors that informed the improvements that were made.3.1 Performance Characteristics of an early JVMThe version of JRockit with which we began our experiments was a complete JVM in the sense that all of the required JVM components were functional. Unlike several other commercial JVMs though, JRockit does not include an interpreter. Instead, all application code is compiled before execution. This could slow down the start of an application slightly, but this approach enables greater performance. JRockit also included a selection of Garbage Collectors and two threading models. Figure 3 shows the performance for increasing numbers of warehouses for a 1-processor and a 4-processor system.d–‘  ‰ ˆ ‡ q y „  y t w q s v v u t sq ’cY¨† u ¥Y ‚ƒ €xYdg"rp d • d (™ “ • Q“ ” – Q“ ” — Q“ ” ™ ˜ ”Q“ ™ ”– ”• ™ hf ge kf ij fm l f hqr omp ncator and synchronization, to enhance the processor scaling of the system. Our experiments were conducted on a 4 processor, 1.6 GHz, Xeon platform with 4GB of memory. The processors had a 1M level-3 cache along with a 256K level-2 cache. The processors accessed memory through a shared 100 MHz, quad-pumped, front side bus. The network and disk I/O components of our system were not relevant to studying the performance of SPECjbb2000, since this benchmark does not require any I/O. Several performance tools assisted us in our experiments. Perfmon, a tool supplied with Microsoft’s operating systems, was useful in identifying problems at a higher level, and allowed us to look at processor utilization patterns, context switch rates, frequency of system calls and so on. EMON gave us insight into the impact of the workload on the underlying micro-architecture and into the types of processor stalls that were occurring, and that we could target for optimizations. VTune permitted us to dig deeper by identifying precisely the regions of the code where various processor micro-architecture events were happening. This tool was also used to study the generated assembly code. The next section describes the performance tools – EMON and VTune – in some more detail.Table 1. System Performance Characteristics for early JVMFigure 3. Performance Scaling with Increasing WarehousesThere is a marked roll-off in performance from the peak at 3 warehouses in the 4-processor case. The JVM can thus be seen to be having some difficulty with increasing numbers of threads. Data obtained using Perfmon is shown in Table 1. While the utilization of the 1 processor is quite good at 94%, the processor utilization in the 4-processor case is only 56%. It is clear that improvements are needed to increase the processor utilization. The context switch and system call rates are two orders of magnitude larger in the 4P than in the 1P. The small processor queue length indicates the absence of work in the system. These aspects along with the sharp performance roll-off with increased threads, all point to a probable issue related to synchronization. It appears likely that one or more locks are being highly contended, resulting in a large number of the threads being in a state of suspension waiting for the lock. While being fully functional, this version of JRockit (we call it early JVM) had not been optimized for performance. It thus served as an excellent test-bed for our studies. The processor scaling seen with the initial, nonoptimized early JVM is shown in Figure 2. It is obvious that we can do much better on scaling. Many other statically compiled workloads exhibit scaling of 3X or better from 1 processor to 4 processors, for instance.œ™ Qœ 8 Ÿ¥ ww¦ ˜—¦ 53wQŸ œ¦Ÿ wQQ3— ¥ › œ œ ™œœ wœ 8w› ¥™ Q 8š œ ™œœ wœ 8w› ‰ˆ s ‚ 3u‡€Š ֘™ º› w› —š QQŸ ›——œ 8QwQŸ œœ› w8w ¥ › œ ¦™Ÿ 5ž ¨w Ÿ™ wž 8¦ ™ž 5Ÿ ¨w †…ƒ ‚ €‹„¨ŠÎ Í Ì Ë Ê ÈÄ Å Ç À Æ Å Ä Ã¿ ¼ Á ¿ ¾ ¼ „u€‹8É ‹½ W‹€½ Y"€‹ÂÀ 8 ¼½ g»â ÛâØ Ýá Ü à ß ÞÝ Ü ÛÚ ÙØ Q"#¨3¨Û ¨ÂQ38¨¤w× Õ Ñœ™ wœ ¨— ›— ¨#› ¥ Qw¦ ž¥ž wQQ˜ ¥ œ œ ™œœ Qœ 8Q#› ˜™¦ w˜ 8› œ ™œœ Qœ 8Q#› ‰ˆ s ‚ wu‡wš™ 5Ÿ 8 ¦ Q— ¥ Q— œ˜ 53¦ ¥ œ ™¦ w¥ 8w— ™ Q¥ 8œ › ™˜ 8š €— †…ƒ ‚ ¨g„w Ô¯ 3¢#¨#„#8xQ83#Q(w ‹‘ Ž ©”¹ ”ª”ª ¸’••”“ ’ “” µ Ž« ’ Ž 5#• #• #w ’ª 8” ( ¨© “” µ•”¯ · Ž¶ Ž© Q• (Q#w“ Ž   ¨± #3” #5° “” µ  ° ³ Ž ² w• (•  5´5” (• €± Ž(Qª5|35” QgQŽ 33wgQ¬ ©  ° £ ’¯ Œ  ®“ ­ – 3 ’ª ¨” (© 8 ‹Œ Ž« ’ Ž ¨ Ž –’”• § Ž 5¨#8 ‹Œ – £”¢   ’ ‘ Ž ¤wQw”  Q¡   #8 ‹Œ –’••”“ ’ ‘ Ž 853#w#w #8 ‹Œ v€ x v ~}{ vt wwt 8t w Y5| xyz wus Ò Ï ÒÑ ÐwÏ Ò Ó ä Ñ QÓ Ð æä åã éä çè äë ê ÐÑ æïðíëî ì3.2 Granularity of Heap LocksThe early version of JRockit performed almost all object allocation globally with all allocating threads increasing a pointer atomically to allocate. In order to avoid this contention, thread local allocation and Thread Local Areas (TLAs) were introduced. In that scheme, each thread has its own TLA to allocate from and the atomic operation for increasing the current pointer could be removed, only the allocation of TLAs required synchronizations. A chain is never stronger than its weakest link, once a contention on a lock or an atomic operation is removed, the problem usually pops up somewhere else. The next problem to solve was the allocation of the TLAs. For each TLA that was allocated, the allocating thread had to take a ”heap lock”, find a large enough block on a free list and release the lock. The phase of object allocation that requires space to be allocated from a free list requires a lock. This lock acquisition and release showed up on all our measurements with VTune as a hot spot, marking it as a highly contended lock. One attempt was made to reduce the contention of this lock by letting the allocating thread allocate a couple of TLAs and putting them in a smaller temporary storage where they could be allocated using only atomic operations by other threads. This attempt was a dead end. Even if the thread that had the heap lock put a large amount of TLAs in the temporary storage, all threads still ended up waiting most of the time, either for the heap lock or that the holder of the heap lock would give away TLAs. The final solution was to create several TLA free lists. Each thread has a randomly allotted ”home” free list from which to allocate the TLAs it needs. If the chosen list was empty, the allocating thread tried to take the heap lock and fill that particular free list with several TLAs. After this, the thread would choose another ”home” free list randomly to allocate from. By having several lists, usually only one thread would try to take the heap lock at the same time and the contention of the heap lock was reduced dramatically. Contention was further reduced by providing a TLA cache; the thread that acquires the heap lock moves 1MB of memory into the cache. A thread that finds its TLA free list empty checks for TLAs in the cache before taking the heap lock. Figure 4 shows the marked improvement in processor scaling in the modified JVM, the JVM with the heap lock contention reduction. Scaling at 2 processors has increased from 1.08X to 1.70X, and the scaling at 4 processors has improved to 2.46X from 1.29X. The perfmon data with these changes is interesting, and is shown in Table 2. The increase in processor utilization and the decrease in system calls and context switches are all very dramatic.3.3 Garbage Collection OptimizationsThe early version of JRockit included both a single and multi generational concurrent garbage collector, designed toFigure 4. Improvement of Processor Scaling with Heap Lock contention scalingˆ ¦ˆ — ‡  S¡— ‡ ƒ ‡ S¡‡ — ƒ ‰ ¡¦©‡ ˆ ‡ ˆ ˆ ˆ ˆ ¡ˆ ¡‡ ˆ ¦‘ ƒ ˆ ‘ ¡ƒ ¡‰ c h ` FHg Y 9 X W i @ f¡pF¦R ™ y‡ F‡ — „ ¦¡† ˆ ¦‘ ˆ ‘ ¡™ ˆ ‡ ˆ ™ ‡ F„ FS‰ ˆ ¡— ˆ ƒ ‡ ¡ FS‰ c b a dSF` Y 9 X W i @ f¡pF¦R ˆ ¡ˆ ƒ † ‰ F¡— ƒ ™  — ¡¦† ˆ — ƒ † ¡¡¦F ‰ ©‡ ˆ ˆ ˆ ˆ ¦ˆ ¡‡ ‰ ¡ƒ ‘ ˆ ˆ ˆ ¦ˆ ¡‡ c h ` FHg Y 9 X W T f¦HV eG ™ y‡ F‡  ‘ ¦¦† ‡   ˆ S¦¡¦† ˆ ˆ ‡ ƒ ¡S¡ƒ ‰ ©‡ ˆ — † „ S¡ƒ † ¡„ — ƒ „ † S¡ƒ c b a dSF` Y 9 X W T 4¡HV UGFigure 5. Impact of Parallel Garbage Collection on Processor Scalinghave really short pause times and fair throughput. Throughput in a concurrent collector is usually not a problem since a full collection is rarely noticed, even less on a multiprocessor system. The problem occurs when objects are allocated in such a fast rate that even if the garbage collector collects all the time on one processor and lets the other processors run the program, the collector still doesn’t manage to keep up the pace. This problem started to hurt performance badly in JRockit when running 8 warehouses on 8-way systems. To solve this, the so-called ”parallel collector” was developed. The base was a normal Mark and Sweep [13] collector with one marking thread per processor. Each thread had its own marking stack, and if a stack is empty the thread could work-steal references from other stacks [5]. Normal pushing and popping required no synchronization or atomic operations, only the work-stealing required one atomic operation. Each thread also had an expandable local stack to handle overflow in the exposed marking stack. Sweeping is also done in parallel by splitting the heap in N sections and letting each thread allocate a section, sweep it, allocate a new section and so forth until all sections were swept. The sweeping algorithm focused on performance more than accuracy, creating room for fragmentation if we were unlucky. A partial compaction scheme was employed to reduce this fragmentation. These GC optimizations resulted in an increase in the re-Figure 6. Impact of Parallel Garbage Collection on SPECjbb2000 Performanceported SPECjbb2000 result in a 4P system, and improved processor scaling from 2.46 to 2.92, as illustrated in Figure 5. The benefits of this were more noticeable at higher numbers of warehouses and therefore lead to a much flatter roll-off from the peak, as shown in Figure 6.3.4 Code Quality ImprovementsSeveral code quality improvements were made during the benchmarking process. A new code generation pipeline was developed and merged into the product. This enabled us to do a lot more versatile and low-level optimizations on code than previously was possible. Based on the SPECjbb2000 characteristics measured and analyzed in the previous section, we were able to identify several patterns at the native code level that were suboptimal. The JRockit team replaced these with better code through peephole optimizations (commonly used for compiler optimizations as in [6, 14]) or more efficient code generation methodologies. While the compiler optimizations listed below are well-known and understood, the requirement here is¾ Àà ¿Ð É Ð Æ Ë Ï Ê Î Í Ì Ë Ê É È Ç Æ ¦¦¡edÉ d8U¦ed¦½S4ž ©¿Ã¾Table 2. 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A Simple Example of Peep-Hole Optimization• ”5Ii˜—• U5y d ™ € – ” “ ‡ "y †  u € y w v u s %iixItr @ P A @ RQ8 I8 0H G F D B A @ 8 0EC 097that the compile time overhead be kept to a minimum since it is a part of the execution time; and as such, not all known optimizations and techniques could be added. These are by no means a complete list of improvements, but give some perspective on things that were done to enhance code quality. 1. Peephole Optimizations: The new JRockit code generator made it possible to work with native code just before emission, i.e. there would be IR operations for each native code operation. Several small peephole optimizations were implemented on this. We present one example of this kind of pattern matching here: Java contains a lot of load/store patterns, where a field is loaded from memory, modified and then rewritten. Literal translation of a Java getfield/putfield sequence would result in three instructions on IA32 as shown in Figure 7(left). IA32 allows most operations to operate directly on addresses, so the above sequence could be collapsed to a single instruction as shown in Figure 7(right). 2. Better use of IA32 FPU instructions: Java has precise floating-point semantics, and works either in 32bit or 64-bit precision. This is usually a problem if one wants to use fast 80-bit floating points that there is hardware support for on IA32, but in some cases we don’t need fp-strict calculations and can use built in FPU instructions. JRockit was modified to determine when this is possible. 3. Better SSA reverse transform: Most code optimizations take place in SSA form. There were some problems with artifacts in the form of useless copies not being removed from the code when transforming back to normal form. The transform was modified to get rid of these, with good results. Register pressure dropped significantly for optimized code. 4. Faster checks: The implementation of several Java runtime checks was speeded up. Some Java runtime checks are quite complicated, such as the non-trivial case of an array store check. These were treated as special native calls, but without using all available registers. Special interference information for these simplified methods was passed to the register allocator, enabling less saves and restores of volatile registers.Table 3. Impact of Better Code Generation on Application Performance5. Specializations for common operations: Array allocation was re-implemented with specialized allocation policies for individual array element sizes. The Java ”arraycopy” function was also specialized, depending on if it was operating on primitives or references and on elements of specific sizes. Other common operations were also specialized. 6. Better Copy Propagation: The copy propagation algorithm was improved and also changed to work on the new low level IR, with all its addressing modes and operations. An example of better copy propagation is shown in Figure 8. These improvements to the JIT were undertaken to reduce the code required to execute an application. It is possible that the techniques used to lower the path length could increase the CPI of the workload, and end up hurting throughput. One example of this would be the usage of a complex instruction to replace a set of simpler instructions. However, Table 3 shows that while the efforts to reduce the path length were well rewarded with a 27% improvement for SPECjbb2000, these optimizations did not hurt the CPI in any significant way. The path length improvement resulted in a 34% boost to the reported SPECjbb2000 result.3.5 Dynamic OptimizationThe initial compile time that is tolerable limits the extent to which compiler optimizations can be applied. This implies that while JRockit provides better code in general than an interpreter, for the few functions that other JITs do choose to compile, there is a risk of under-performance. 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